Learn French: Il y a un mur autour. - There is a wall around it.

The lesson teaches complex prepositions like autour de (around), but the de is only used when you name the specific object that follows, like in autour de la maison (around the house). When the object is just an implied 'it', you drop the de and use autour all by itself.

Where is the word for 'it' in the French sentence?

There isn't one! In English, we need to say 'around it', but French doesn't use a literal translation here. The word autour used on its own naturally translates to 'around it' or 'all around' when the place is already known from context.

Can I say autour de ça to mean 'around it'?

It is technically understood, but native speakers rarely say autour de ça for simple locations. Dropping the de and using just autour sounds much more natural and is the standard way to describe something being 'around it'.

Would Il y a change if we were talking about multiple walls?

No, il y a is a fixed expression. It means both 'there is' and 'there are'. If there were several walls, you would say Il y a des murs autour, keeping the exact same starting phrase.