This is the 11765th most frequent Russian word.
займётся
"Will take care of" or "will start dealing with."
The word 'займётся' is used in future tense to express that Marina will commit or start working on the project.
Марина займётся проектом после совещания.
Marina will take care of the project after the meeting.
Here, 'займётся' conveys an action scheduled for the future regarding the preparation of documents.
Он займётся подготовкой документов завтра утром.
He will deal with preparing the documents tomorrow morning.
In this case, 'займёшься' asks about the time for beginning the action of cleaning the room, utilizing the second person singular future tense.