It is formed if + present simple + easy future.
It is used when a situation is real or possible:
If it rains today, I'll stay at home. Here are
some examples translated.
USES
We use the first conditional when
we are talking about future events
that are possible.
examples
Lisa will be very happy if she wins the prize.
(Lisa estará muy contenta si gana el premio.) If
it rains, then we will stay at home. (Si llueve nos
quedaremos en casa.) You will always be able to
take another test if you fail. (Siempre podrás
presentar otro examen si no pasas.) If I see
Sam, I will ask him to give you a call. (Si veo a
Sam le pediré que te llame.)