This is the umbrella rule under which Apple's more specific content restrictions sit — content in your app, whether you wrote it, licensed it, or users posted it, can't cross into being genuinely offensive, obscene, or in bad taste in a way most people would find upsetting.
Broad or ambiguous submissions that include crude humor, shock content, or edgy meme-style material aimed at a general-audience rating often get caught here even when no single specific sub-rule clearly applies.
"Your app contains content that is offensive, insensitive, or in poor taste, per guideline 1.1. Please remove or revise the flagged content and resubmit."