The review queue is where things other people proposed wait for a decision. Nothing in it has taken effect yet, and nothing in it goes away on its own.
Pending Reviews is reached from the menu under your name, and the bell in the top bar turns red while anything is waiting - hover it and the dropdown says what. Two kinds of entry land there for an organizer: someone asking to join a group you run, and someone proposing a change to something they cannot edit themselves. Each entry names who it is about and what it concerns.
Open Details before deciding on a proposal
The line says what the proposal is about; only the detail page says what it would actually change.
Take a proposal in parts if you want
On the detail page, apply the rows that are right and deny the ones that are not. There is no requirement to accept a proposal whole.
Clear the queue regularly
A request sitting unanswered is a member who reached out and heard nothing. The bell stays red until the queue is empty, for exactly this reason.
Proposals are people offering to help
A join request is someone who found your group and wants in. A proposal is someone who spotted a wrong date or a missing translation and took the trouble to suggest a fix. Both are cheap to answer and expensive to ignore: a request sitting unanswered for a week is the clearest signal a group is dormant.