This is the 22nd most frequent Russian word.
они
"They."
Here, 'они' is used as the pronoun for 'they' referring to a group of people performing the action.
Они гуляют в парке.
They are walking in the park.
In this sentence, 'они' points to a group that experiences a reaction to an outcome, maintaining its role as the subject.
Они были удивлены результатами.
They were surprised by the results.
The pronoun 'они' is used in a question indicating an inquiry about the identity of a group.