Learn Italian: Mi lavo il viso nel lavandino.

In Italian, when you do an action to your own body, you do not use possessive words like 'my' or 'your'. Instead, the reflexive pronoun mi already tells us whose face it is, so you just use the definite article il (the).

Why do I need mi here? Can I just say lavo il viso?

If you just say lavo il viso, an Italian speaker might wonder whose face you are washing! Using the reflexive pronoun mi (to myself) makes it clear that the action happens to your own body.

How is nel formed?

Nel is what happens when you combine the preposition in (in) with the definite article il (the). Since lavandino (sink) is a masculine word starting with a consonant, it uses il, which merges with in to become nel.

I learned that 'face' is faccia. Can I use that instead of viso?

Yes, absolutely! Both words mean 'face'. Viso sounds slightly softer or more elegant, while faccia is the everyday standard word. If you use faccia, just remember it is feminine, so you would say Mi lavo la faccia.