Learn Italian: Luca mi accompagna nel palazzo. - Luca accompanies me into the building.

In English, we say "accompanies me", putting the pronoun after the verb. In Italian, direct object pronouns like mi (me) almost always go directly before the conjugated verb. So, Luca mi accompagna literally follows the order "Luca me accompanies".

What happens if I want to say "Luca accompanies you" into the building?

You would just swap the pronoun mi for ti (you). The sentence becomes Luca ti accompagna nel palazzo. This uses the exact same pattern of putting the object pronoun right before the verb.

Why is it nel palazzo instead of just in palazzo?

Nel is a combined word made from the preposition in (in or into) and the masculine singular word for "the", il. Because we need to include "the" to say "into the building", Italian combines in and il into nel.

Doesn't palazzo mean "palace"?

It can mean "palace", but in everyday Italian, un palazzo is most often used to refer to a standard large building, an apartment building, or a multi-story office block.