The Second Conditional is used to talk about unreal, impossible things in the present or the future:
If I were you, I would do more exercise. (But I'm not you, so it's very unlikely. However, I'm advising you.)
If I won the lottery, I would buy a car. (I don't have a ticket, but I might buy it in the future, so right now I'm dreaming about winning in the future.)
If I studied, I would pass my exam. (It might still happen.)
If I had a lot of money, I could travel round the world. (It's highly improbable.)
If clause = condition
if + subject + past simple,
main clause = result
subject + would / could + infinitive