Help

Hey!

Could someone explane me what means this red little box with mostly GM? (At pro players)

It is the players fide title. GM = grandmaster, IM=international master, and so on

how do you get a title? through a tournament?

Different titles have different requirements. For GM it takes at least 3 tournaments (edit, looks like 2 now) and there are multiple specific requirements about the length of the tournament, types of players, ratings, etc.

It's worth noting that chess.com doesn't give any titles, it only recognizes titles issued by e.g. FIDE and USCF. The GM title is a FIDE title. Those players earned it while playing in FIDE rated tournaments and afterwards sent chess.com proof. Then chess.com staff adds the GM status to their chess.com account.

Here's how chess.com does titles:
https://support.chess.com/customer/en/portal/articles/1444932-does-chess-com-offer-benefits-for-elite-or-titled-players-

You can read about FIDE titles here:
https://en.wikipedia.org/wiki/FIDE_titles#Grandmaster_(GM)

You can find specific requirements for FIDE titles here:
https://www.fide.com/fide/handbook.html?id=198&view=article