Breakdown of Он пришёл за минуту до звонка.
он
he / it (for a masculine noun) / it (for a neuter noun)
минута
minute
до
before, until
прийти
to arrive (on foot, pf)
Questions & Answers about Он пришёл за минуту до звонка.
How does the phrase за минуту до звонка work here to mean "a minute before the bell"?
This is a set structure for expressing how long before an event something happened. You use за + the amount of time in the Accusative case (минуту) + до + the event in the Genitive case (звонка). Literally, it is like saying "in a minute before the bell."
Why use за ... до instead of just перед (before)?
The preposition перед just means "before" in a general sense (like перед звонком - before the bell). But when you want to specify exactly how much time passed before the event (here, exactly one minute), you must use the за [amount of time] до [event] structure.
Why is the Genitive form of звонок (bell) звонка and not звонока?
The word звонок has a "fleeting vowel." When adding case endings to many masculine words that end in -ок, -ец, or -ень, the last vowel drops out. So the base звонок loses its о and becomes звонка in the Genitive case.
Why use the perfective verb пришёл instead of the imperfective приходил here?
The perfective пришёл focuses on a single, successfully completed action with a result (he arrived and was there for the bell). The imperfective приходил would imply either a repeated habit (he used to arrive) or a round trip (he came and then left).