Learn Polish: Szef zawsze przychodzi do biura za dziesięć ósma. - The boss always comes to the office at ten to eight.

To express minutes to the hour, Polish uses the preposition za followed by the number of minutes in the Accusative case (dziesięć). The upcoming hour is always in the Nominative case (ósma), acting like an adjective matching the hidden feminine word godzina (hour). You can think of it as meaning in ten minutes it is the eighth hour.

Why isn't there a word for at before the time in this sentence?

Normally, you use the preposition o to mean at a certain time, like o ósmej (at eight). However, when telling time using za (to) or wpół do (half past), you completely drop the o. You just say za dziesięć ósma directly.

Why does biuro change to biura in this sentence?

The word for office is biuro, which is a neuter noun. The preposition do (to or into) always forces the noun that follows it into the Genitive case. For neuter nouns ending in -o, the Genitive ending is -a, which gives us do biura.

Why use przychodzi instead of idzie if both involve walking?