Learn Polish: Jestem przed kinem. - I am in front of the cinema.

After the preposition przed (in front of), you must use the Instrumental case. For a neuter noun like kino, the ending changes from -o to -em, making it kinem.

I have seen przed used to mean 'before' for time. Does it also mean 'in front of' for places?

Yes! The word przed is used for both time and space. Just like it means 'before' in time, it means physically 'in front of' when talking about a location.

Why is the word ja (I) missing before jestem?

In Polish, you usually drop subject pronouns like ja (I) because the verb form already tells you who is doing the action. Since jestem can only mean 'I am', adding ja is not needed unless you really want to emphasize it.

If I walk inside, do I say 'Jestem w kinem'?

No, because different prepositions require different noun endings (cases). While przed (in front of) triggers the Instrumental case (kinem), the preposition w (in/inside) triggers the Locative case, making it Jestem w kinie.