What is Pawn Structure??

Anything will help :)

Isolated Pawns, doubled Pawns, backward Pawns, open, semi-open and hybrid files, rams, duos, levers, chains...

Ideally you will want to keep your pawns together in groups that protect each other and control territory on the board.

Whenever you make a pawn move you got to be carful to not disrupt the structure.

The more pawns protecting eachother the better. This frees your other pieces for other tasks.

Here's a small example: White has an amazing pawn-structure where the king can single-handedly defend all of them. Black's structure is totally disrputed. There's three islands, several doubled pawns and it would be really hard to defend those.

Read Kmoch's "Pawn Power in Chess": your answer is there.

You can just ignore it (pawn-structure) if only wanting to be average-player like myself.

If want to be strong (1900+) chess-player then is important to learn the principles of structure.

Attack your opponent's weak, backward, or isolated ones, is a good idea to get started with.

Only if you speak fluent Kmochian. 

Everyone of those ten (or less?) original terms he uses is clearly explained in plain English, or whatever language the translation.

If your language is a neolatin one (Spanish, Italian, Potuguese or French), or if you studied latin in high school or biology/medicine at the university (leucocites, melanine...), those oh-so-obscure terms are easily understandable even without the clear explanation.

In my personal experience, Kmoch's book is the best one a beginnerish player can chose as a starter for Pawn play and structure: it takes into account limited parts of the structure and shows how changing them affects the game with clear and never too complex examples, also examining how each piece can coordinate with those limited parts of the structure.

All the other books on this topic which I could read are too much concerned with how complete an information they transmit to the reader, who seems to be supposed to learn an enciclopedic knowledge of all possible complete structures through that single book they're reading. The knowledge ginven in Kmoch's book is instead divided into managable chunks, and the inexperienced player can try to combine the studied pieces of the whole picture at the board while developing an understanding of Pawn structure and related strategies through his/her own experience of play: for me it was THE eye opening book, and after reading it twice I started playing whole games of Chess instead of moving the pieces around and looking for random tactics.

Andy Soltis's newly reissued Pawn Structure Chess is probably more accessible for the average chess.com reader and has also received sterling reviews.

I've studied Latin and Greek, I've worked in medical research, I'm more than capable of handling complex material. Kmoch's book may contain plenty of great information, but his writing style is indefensible. 

In general I would say that: at first (opening/midgame) pawns mainly support your mindor pieces for control over the center. Later on (midgame/endgame) the pawns themselves become more important, and the placement of isolated/passed pawns/pawnchains may well be decisive to the outcome.

Besides this I agree with paulgottlieb and netzach, although I believe on <1900 a basic understanding of pawnstructures would be important/helpful. It is (at least for me it is) relatively difficult because of the many exceptions to the theories, and even more so because of the difficulty to get the desired structure during play (without too much compromise). It's probably best to focus on different things for now.

I read the book in English, while my language is Italian: I had no problem whatsoever with Kmoch's writing style.

I also studied Latin and Biology, not Greek, and worked in bio research, so we're of similar culture. Probably it's more a matter of taste.