0 Conditional - General truths
If I study, I learn.
1st Conditional - Future - likely , real
I study , I will learn.
2nd Conditional - Present or Future, not likely , unreal - hypothetical.
If I studied , I would learn ( but I don't study so I don't learn ) .
3rd Conditional - Past
If I had studied , I would have learned ( but I didn't study, so I didn't learn ) .