This is the 5530th most frequent Russian word.
покупают
"(They) buy."
In this sentence, 'покупают' is used in present tense to describe a habitual action performed by a group of people.
Они покупают фрукты на рынке каждый день.
They buy fruits at the market every day.
Here, 'покупают' refers to an action performed by unspecified individuals in the present tense, suggesting a general practice.
Люди покупают билеты на концерт заранее.
People buy tickets for the concert in advance.
The word 'покупают' is used to indicate an action by a collective subject occurring in the present moment.