What is a winning position in chess? I am new to chess, so I have some difficulties on understanding some concepts. For example, by watching games usually I hear that a player has a winning position, or a better position respect to the other player. 

But how do I understand if my position is good? What are the signs that a overall position of the pieces on the board is a good position? 

Thanks in advance
This is very broad, but what is winning is very related to your strength. I have seen plenty of beginners, who could not win even up a full queen.

For example, a beginner might need a queen, or more, to be able to win a position. I have been a "regular" Master for more than 30 years, so it might just one pawn, but the right pawn. :)

By comparison, I used to read Garry Kasparov's notes to his games in the Informants, and he would use the symbol +- (winning) in positions that looked barely better to me. His sense of winning, of course, was correct, but it was much more refined than mine. 

All of this still means only so much in practice because as they say, "the hardest thing to do in chess is win a won position".

Understanding when your position is good or won simply comes with time, study, and practice. It is too open a subject to be more specific.