Learn Swedish: Han var sjuk i helgen. - He was sick this weekend.

Not at all! Unlike English, which changes between 'was' and 'were', Swedish verbs stay exactly the same no matter who is doing the action. It is jag var (I was), han var (he was), and de var (they were).

I learned earlier that var means 'where'. Why does it mean 'was' here?

The word var actually has two completely different meanings! It is the question word 'where', but it is also the past tense of the verb att vara (to be). You can tell which one it is from the context. Since it comes right after the subject han (he), it's acting as the verb 'was'.

The translation says 'this weekend', but isn't helgen literally 'the weekend'?

Yes, helgen is the definite form of helg (weekend). The phrase i helgen literally means 'in the weekend', but it is the standard Swedish way to say 'this weekend'. Because the verb var (was) is in the past tense, we know it specifically means this past weekend.

If I wanted to say 'They were sick', would the word sjuk stay the same?