"Who are you looking for?"
Translation:Ketä sinä etsit?
Vice versa. Both can be "who" (as in this example) but in addition they have slightly different use cases, roughly like this:
- kuka – who, which
- ketä – who, whom.
- kuka auttaa? – who helps/who is helping?
- ketä autat? – who are you helping?
- kuka auttaa ketä? – who's helping whom?
Finnish may also use other interrogatives, e.g.
- kenelle kirje on? – whom is the letter [addressed] to?
I know it's not straightforward but don't worry too much about them in the beginning. You'll get them eventually :)