Hi! Thank you for the question!
Personally I'd interpret this as simple shapes suggesting people/silhouettes: no identifying details but you know it's people and not sacks of potatoes. As simple as possible: Minimum Viable Silhouette. If you google "crowd silhouette" you should get good examples of what we mean.
This rule was put in place so people don't overwork themselves drawing many different characters. So please do not go into detail with this. I'd highly suggest that if you do want to flex your skills, you might want to focus you attention to the rest of the CG: whether this is the main character or the background.
Happy to clarify if that doesn't fully answer your question!