This summary is not the rule. The rule text controls.
Judges are allowed to get paid for outside activities, like teaching a class, writing a book, or giving a speech, as long as those activities are otherwise permitted under the judicial conduct rules. The pay they accept has to be reasonable for the work involved.
There's an important limit, though. A judge can't accept payment if it would make a reasonable person question whether the judge can still be fair, honest, or independent on the bench. So if the payment comes from a source that could look like it's trying to influence the judge, or if the amount seems excessive for the activity, the judge should turn it down.
This rule exists to keep judges from being influenced by money in ways that could affect their decisions in court. It lets judges engage in normal outside activities and get fairly compensated, but it stops arrangements that could create doubts about whether the judge is truly neutral.