Someone talk me through seeing brand visibility in chatgpt?

There's no dashboard for it, so most people do it by hand at first. Write down 20 or so questions a buyer would actually ask ("best x for small teams", "x vs y"), run them in a temporary chat so your history doesn't skew it, and record whether you're mentioned, where in the list, and which sites it cites. Run each one a few times, the answers change between runs. Repeat monthly and you've got a trend you can trust more than any single answer.