Si no reps res avui, demà pots trucar a correus o a la secretària.

not

Breakdown of Si no reps res avui, demà pots trucar a correus o a la secretària.

• avui: today
• demà: tomorrow
• a: to

Questions & Answers about Si no reps res avui, demà pots trucar a correus o a la secretària.

Why is it si no and not sinó?

Because they are two different things:

• si no = if not
• sinó = but rather / except

In your sentence, Si no reps res avui... means If you don’t receive anything today..., so it has to be si no as two words.

Compare:

• Si no reps res avui, demà pots trucar... = If you don’t receive anything today, tomorrow you can call...
• No trucis a correus, sinó a la secretària. = Don’t call the post office, but rather the secretary.

So here si no is correct because it introduces a condition.

Why is reps used here? What verb is it from?

Reps is the 2nd person singular present tense of rebre (to receive).

So:

• jo rebo = I receive
• tu reps = you receive
• ell/ella rep = he/she receives

This is an irregular verb, so the form is not something fully predictable from the infinitive unless you learn it.

In the sentence:

• Si no reps res avui... = If you don’t receive anything today...

the subject is an implied tu (you), which Catalan often leaves out because the verb form already shows the person.

Why does res mean anything here, if I learned that it means nothing?