I'm new to soccer, can someone help me understand something?

I need to know what the positions are and what is commonly requires of them. Lay them out so I can understand, like I said I'm new to the sport so I won’t understand all the soccer (or football) lingo. Also, is soccer like all the other sports when is comes to how many of one position you can have on the field of play, or can teams have varying positions on the field, like Team A will have 2 strikers while Team B will have only 1? Is this allowed? Thanks! 10 points to the most helpful.