LATTANZIA0414: ???? season pass ???
It's generally a one-time purchase that gets you any upcoming content for a game for that price. Usually ends up being cheaper than buying the content as it's released.
You should buy it if you want to. Or don't buy it if you don't. As a general rule, if you'd likely buy the content for full price as it's released, then you're probably better off paying for the seasons pass. If you tend to wait until content is discounted before buying, then it's probably not worth getting the seasons pass.
Personally, I hate the damned things because it's basically like a loot box. You don't know exactly what you're going to get and it's happened more than once that a developer has promised lots of upcoming content and then not delivered, making it a waste of money.