Se o pepino estiver fresco, eu também vou comprar repolho para a salada.

If the cucumber is fresh, I am also going to buy cabbage for the salad.

Breakdown of Se o pepino estiver fresco, eu também vou comprar repolho para a salada.

• eu: I
• estar: to be
• comprar: to buy
• ir: to go (future auxiliary)

Questions & Answers about Se o pepino estiver fresco, eu também vou comprar repolho para a salada.

Why is estiver used instead of está?

Because this sentence is talking about a possible future condition.

After se meaning if, Portuguese often uses the future subjunctive when the condition is about the future:

• Se o pepino estiver fresco... = If the cucumber is fresh / if the cucumber turns out to be fresh...

Using está would sound wrong in this kind of future-looking sentence.

A useful contrast:

• Se o pepino estiver fresco, eu vou comprar repolho.
  Future possibility

• Se o pepino está fresco, eu compro.
  More like a general or repeated situation, and not the best match for this context

What tense or mood is estiver, and what verb does it come from?