"The cheese is for lunch."

[Klyamada]

Any tips on when to use "por" or "para " when translating the word "for" in English?

[Paulenrique]

Preposition varies a lot from language to language so it's hard to give a bunch of rules on it. If something is "toward/directioned to" translate "for" as para and when it is "in behalf of someone/something, by, per, a (day)" translate "for" as por

[SmarandaLu]

Why is para o almoço correct, but not pelo almoço?

[ronkisimo]

same question?

[Paulenrique]

In this case, "pelo" = in behalf of