This is the 40th most frequent Finnish word.
jos
"Jos" means "if" in English.
"Jos" is used here as a conjunction introducing a conditional clause, equivalent to "if" in English.
Jos sataa, otan sateenvarjon mukaan.
If it rains, I'll take an umbrella with me.
"Jos" is used here to introduce an indirect question, similar to "if" in English.
Hän kysyi minulta, jos voisin auttaa häntä.
He asked me if I could help him.
"Jos" forms a part of the adverb "Joskus," meaning "sometimes," not related to conditional or interrogative usage.