You may very well ask 'What is a pub quiz?'
It is a fun general quiz, consisting of six rounds of ten questions. The first round is usually 'General Knowledge', three rounds will cover a variety of subjects, there is usually a picture round and the last round is something sound based e.g. music or theme tunes.
Something to bear in mind is that as these are fun quizzes, you will not be seeing any 'school' style subjects (unless that is what you want, of course).