We use second conditional to talk about hypothetical, unreal, imaginary situations.
A second conditional sentence consists of two clauses, if clause and main clause.
if + past simple + would
If I had 200 dollars, I would buy a mobile phone.
If we use"if" clause first, we usually use a comma after if clause.
If I were you, I would help that man.
If we use "if" clause second, there is no need for a comma.
I would help that man if I were you.
If birds had wings they would be able to fly.
He would be healthier if he didn't smoke.