Learn Turkish: Kendine iyi bak, hastasın. - Take care of yourself, you are sick.

Kendi means 'self' and the -n makes it 'your self'. The -e at the end means 'to' (the dative case). The verb bak (to look) requires this 'to' ending. So literally, you are saying 'look well to yourself'.

I thought bak meant 'look'. Why is it translated as 'take care' here?

The verb bakmak usually means 'to look'. But when you 'look to' someone or something, it takes on the meaning of 'looking after' or 'taking care of' them. Kendine iyi bak is a very common everyday expression for saying goodbye or wishing someone well.

Doesn't iyi just mean 'good'? How does it work as 'well' in this sentence?

In Turkish, many adjectives can be used directly as adverbs without changing their form. İyi means both 'good' and 'well'. Here, it describes how you should look after yourself.

Where is the word for 'you' in hastasın?

Turkish adds endings to words to show who is being talked about. The base word is hasta (sick), and the -sın ending means 'you are'. You could say sen hastasın, but dropping the sen is the most common and natural way to say it.