A Safety Circle contains at least five adults (at least two who aren’t family) who agree to help your kid stay safe. These are people your kid trusts and can talk to about uncomfortable things.
I want to harp on “agree.”
For a Safety Circle to work, you must explicitly invite people to it, and those people must actively agree to be in it. The Safety Circle has a critical job. The people in it need to know what that job is and agree to do it.