Hypnotic things either relate to hypnosis — putting people under spells — or anything that is mesmerizing or spellbinding.
You know how hypnotists put people under spells and then make them quack like a duck, or do something equally silly? Hypnotic things relate to hypnosis — like a hypnotist's calm, entrancing, hypnotic voice — or other things that tend to grab people's attention in a similar way. The voice of a powerful public speaker could be described as hypnotic. Great music that you can’t turn off could also be considered hypnotic. Anything hypnotic has a powerful hold on your attention.