Learn Portuguese (Portugal): Eles não conhecem a zona onde cresceste. - They do not know the area where you grew up.

onde is a relative pronoun linking the two halves of the sentence. It translates to 'where' or 'in which' and points directly back to the physical place mentioned right before it, a zona (the area). Unlike adjectives, onde is invariable, meaning it never changes its spelling to match the gender or quantity of the noun it refers to.

Could I say a zona em que cresceste instead?

Yes, absolutely! When talking about a physical location, onde (where) and em que (in which) mean the same thing and are often interchangeable. Using onde just sounds a bit more natural and direct in everyday speech.

Why does the sentence use conhecem instead of sabem for 'know'?

This is a great time for a quick refresher! Portuguese has two verbs for 'to know'. We use saber for knowing facts, information, or how to do something. We use conhecer for being familiar with people, places, or things. Because 'the area' is a physical place, conhecem is the correct choice here.

How do we know it means 'where you grew up' if the word for 'you' isn't there?

The verb ending tells us exactly who did the action! cresceste is the simple past tense of crescer (to grow). The -este ending is only ever used for tu (informal 'you'). Because this ending makes it so obvious who we are talking about, it is completely normal to drop the pronoun entirely.