Si [if] followed by present indicative + main clause [command/request/advise] : Spanish language lesson

To express a command/request/advice that depends on a condition, we use this structure with the conjunction si:

Si (if) + condition in El Presente, ... affirmative or negative command/request/advice.

Have a look and listen to these examples with affirmative commands/requests/advice in the main clause:

Si ves a Juan, dile que venga.
If you see Juan, tell him to come.

Si cocinas esta noche, ponte el delantal.
If you cook this evening, put the apron on.

Si estudias español, compra un buen diccionario.
If you study Spanish, buy a good dictionary.

Si vosotros salís, cerrad la puerta.
If you go out, lock the door.

The condition is introduced by si and the command/request/advice is expressed in El Imperativo.

Have a look and listen to these examples with negative commands/requests/advice in the main clause:

Si bebes, no conduzcas.
Don't drink and drive. (lit: If you drink, don't drive.)

Si vas a la playa, no tomes el sol demasiado.
If you go to the beach, don't sunbathe for too long.

Here, the negative command/request/advice is expressed in El Presente de Subjuntivo.

The introductory clause with si (if) expresses the condition for the action in the main clause to be met.