This is the 3136th most frequent Russian word.
купили
"Bought."
The word 'купили' is used as the past tense form of the verb 'купить', meaning 'to buy', in the first person plural form.
Мы купили новую машину вчера.
We bought a new car yesterday.
Here, 'купили' represents the past action of purchasing by a group of people (third person plural).
Они купили хлеб и молоко вечером.
They bought bread and milk in the evening.
In this sentence, 'купили' is used in the past tense for the second person plural or formal singular, often applied in interrogative context.