Learn Polish: Nowe mieszkanie szefa było za ciasne. - The boss's new flat was too cramped.

Yes! Both za and zbyt mean too when expressing that something is excessive. Za is more common in spoken, everyday Polish, while zbyt is slightly more formal or written. Nowe mieszkanie szefa było zbyt ciasne means exactly the same thing.

Why do nowe and ciasne end in -e?

Both of these adjectives are describing the noun mieszkanie (flat). Because mieszkanie is a neuter noun and acts as the subject of the sentence, the adjectives must take the neuter ending, which is -e.

Why is the word for boss written as szefa here instead of just szef?

Szefa is in the genitive case, which Polish uses to show possession (similar to adding an apostrophe-s in English). Mieszkanie szefa literally translates to the flat of the boss.

Why is the past tense verb było instead of był?

In the Polish past tense, verbs have to match the gender of the subject. Since the subject is mieszkanie, which is a neuter noun, you have to use the neuter form było. If the subject were masculine, like pokój (room), it would be był za ciasny.