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
some examples translated
If it rains today, I'll stay at home. Si llueve hoy, me quedaré en casa. If
he is busy now, I will come back tomorrow. Si está ocupado ahora,
regresaré mañana. If I have time, I'll visit my parents this afternoon.
Si tengo tiempo, visitaré a mis padres esta tarde. If it is warm
tomorrow, we'll go to the beach. Si está caluroso mañana, iremos a la
playa. If it is cold, you must wear warm clothes. Si está frío, debes
usar ropa abrigada.
STRUCTURE
POSITIVE
The first conditional is formed with the This
simple in the 'if-clause' (sentence 'If') and
the simple future in the 'main clause' (Main
sentence).
[If... + Present Simple] + [will + verbo principal]
Si gano la lotería, me compraré una casa. If I
win the lottery, I will buy a house