Level A2
First Conditional: real future
First conditional: if (or when) + present, will in the other part (If it rains, I will stay home). After if and when about the future there is no will.
If it rains, I will stay home.
Look: If it rains, I will stay home. Rains after if, will in the other part.
Forms
It will rain.— on its own, the future takes willIf it rains, I will stay home.— after if: no will, the action word is in the present; the other part keeps willWhen she comes, we will eat.— the same after when
A common mistake
Wrong: If it will rain, we'll stay home.
Right: If it rains, we'll stay home.
So many people say If it will rain, but after if there is no will. We say: If it rains, we'll stay home.
More examples
I'll call you when I land.
When works the same way: I'll call you when I land.
If you come, I'll be happy.
One more: If you come, I'll be happy. Come after if, will in the other part.