In a way it is a lot like the subjunctive in Spanish, but we simply don't use it so much. One famous literary subjunctive line is: "if I were a rich man." Were is used there as the subjunctive for the same reason it would be in the subjunctive in Spanish. "It is important that you be there" is another example that is basically the same as the Spanish. I am not a grammar expert so hopefully someone can give you a better explanation.

We avoid the subjunctive as much as possible! Often it's identical to the indicative form, so we don't even notice we're using it. In other cases it takes the form of the past simple. A good way to recognise a subjunctive is if you see a past simple form, but it's clear that we are not talking about past time. For example: It's getting late. It's time we went home. I'm a bit cold. I'd rather you didn't open the window.