This is the 11936th most frequent Polish word.
kupił
"Bought."
Here, 'kupił' is used in the past tense to indicate that Jan performed the action of buying a car.
Jan kupił samochód.
Jan bought a car.
In this question, 'kupił' is used in the past tense to inquire about the action of buying a computer.
Czy kupił on nowy komputer?
Did he buy a new computer?
'Kupił' is used in a conditional past tense here to refer to a hypothetical situation.