This is the 83rd most frequent Persian word.
کردن
"To do" or "to make."
In this sentence, 'کردم' is used as the past tense of the verb 'کردن,' which means 'to do,' here indicating the action of exercising.
من امروز ورزش کردم.
I exercised today.
'کردن' can be associated with performing an action, as seen in conjunction with 'کاری.'
او تصمیم داشت کاری مهم انجام بدهد.
He had decided to do something important.
Here, 'کردن' implies engaging or carrying out the task described as 'project.'