That's pretty broad - the bill doesn't limit it to sexual content so it could be anything. A picture of a muslim praying, an ad for guns, an article that says nice things about Hillary Clinton, Trump's official re-election site.
Some people might think a picture of a woman in a bikini is offensive, others might not find a picture of people having sex offensive. This would get tied up on court for years and has no chance of ever being enforced in the unlikely event a state like Maine passes it. I could see Utah or Alabama passing something like this, but it has no chance in Maine.