This is the 12524th most frequent Russian word.
коллективом
"Коллективом" means "as/by/with a team or collective."
In this sentence, "коллективом" is used to indicate that the action was performed collectively, as a group.
Мы решили проблему коллективом.
We solved the problem as a team.
Here, "коллективом" specifies that the organizing team, or group within the company, arranged the meeting.
Собрание было организовано коллективом компании.
The meeting was organized by the company team.
In this case, "коллективом" implies collaboration or working alongside a team to accomplish tasks effectively.