What are best openings for beginners?

what is the caro kahn?

It's Caro-Kann.  It's a good defense for Black against 1.e4.

First understand that there is no "best" opening.
However, there are many good, very playable openings, albeit with lots of subjective and ultimately inconclusive debate over which are better than others.  In choosing an opening the two issues of most concern tend to be not only its objective effectiveness (irrespective of the player's experience or skill level), but also (particularly for lower rated players) how easy or difficult the opening is to learn and play.  These are the essential points addressed by GM Hikaru Nakamura’s “Chess Openings Tier List” series of videos…

Chess Openings Tier Lists – GMHikaru (complete, beginner thru GM)…
https://www.youtube.com/watch?v=M9CwH47r6og&list=PL4KCWZ5Ti2H43-gcoByRnZs5fVR_Lg133&index=4

In the tier lists, chess openings are classified in terms of their appropriateness vis-a-vis player skill level -  i.e., beginner vs intermediate vs GM, etc.  For a given player level, the openings are rated and categorized into six "tiers", from "legendary" to "garbage" (the latter being an unfortunate choice of terms, IMO).  These qualifiers are used in the context of not only how much so-called "theory" (i.e., documented variations) the particular opening encompasses, but also how tactical versus positional in character it tends to be, which is generally dictated by how "open" versus "closed" the center is at the conclusion of the opening.  Openings with less theory to learn and which are primarily tactical in character are generally recommended as an appropriate starting point for less experienced players.  So an opening they refer to as "garbage" (i.e. less 'appropriate' - a better term!) for a beginner may in fact be more appropriate for higher rated players who are assumed to possess a more highly developed requisite knowledge base and skills set.  For each of the openings discussed note also whether the evaluation is from White's or Black’s perspective.

For beginner-intermediate players check out ‘GothamChess’ (IM Levy Rozman) on YouTube for recommendations and quick exposure to a variety of openings...
https://www.youtube.com/watch?v=NFod-ozimmM&t=103s
https://www.youtube.com/watch?v=Qdyik5UwBtM
https://www.youtube.com/results?search_query=gothamchess+openings
https://www.youtube.com/watch?v=rmbU97iftC8&list=PLBRObSmbZluTpMdP-rUL3bQ5GA8v4dMbT

Chess opening – Wikipedia…
https://en.wikipedia.org/wiki/Chess_opening

Chessable’s Guide to Chess Openings (for White & Black)...
https://www.chessable.com/blog/opening-guide/

Openings Guides – SimplifyChess.com...
https://simplifychess.com/homepage/openings.html

‘Hanging Pawns’ openings videos on YouTube…
https://www.youtube.com/c/HangingPawns

For more on openings fundamentals and principles, as well as specific openings, see...
Chess Openings Resources for Beginners and Beyond...
https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond

more helpful chess resources, including openings and book recommendations, in my blog...
https://www.chess.com/blog/RussBell

“Easy” Openings for White

Here are some of the 'easier' (i.e., less 'theory' to learn) 1.e4 openings for White.....which are sound and very playable at the amateur, club level.  All of these 1.e4 games are so-called "Open" or "Semi-Open" games, where the center is not typically closed, when lines (files, diagonals) can more readily be opened, thus tending to lead to games of a more tactical character (as opposed to maneuvering, positional chess)... 

Scotch Game
https://www.youtube.com/results?search_query=scotch+game
https://en.wikipedia.org/wiki/Scotch_Game

Ponziani Opening 
https://www.youtube.com/results?search_query=ponziani+opening
https://en.wikipedia.org/wiki/Ponziani_Opening

Vienna Game & Gambit
https://www.youtube.com/results?search_query=vienna+game
https://en.wikipedia.org/wiki/Vienna_Game

Introduction To The Vienna Game & Gambit
https://www.chess.com/blog/RussBell/introduction-to-the-vienna-game-gambit

The Italian Game – more challenging to learn (i.e., more 'theory') than the above, but a very rich and sound opening complex, which can be played for the rest of your chess career and at the highest levels...

Introduction to The Italian Game & Evans Gambit
https://www.chess.com/blog/RussBell/introduction-to-the-italian-game

Bishop's Opening – this is not an opening per se, but an opening 'gateway', leading to a rich variety of openings (useful for keeping your opponents guessing!) including several of the above, especially the Italian Game...
https://www.youtube.com/results?search_query=bishop%27s+opening
https://en.wikipedia.org/wiki/Bishop%27s_Opening

If you prefer to play 1.d4 as White, then perhaps the 'easiest', yet effective, openings to learn are... 
The Stonewall Attack - I consider this to be a precursor to the London System (there are some similarities, and the Stonewall is easier to learn), and very playable at the amateur, club level...
https://www.chess.com/blog/RussBell/stonewall-attack

Introduction to the London System & Jobava London System
https://www.chess.com/blog/RussBell/the-london-system

Chess Openings Resources for Beginners and Beyond…
https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond

For more good chess resources, be sure to check out my blog...
https://www.chess.com/blog/RussBell