It says "Dress Up", as in dressing up an avatar, but for some reason, human avatars are currently disabled. Quite a few of the users on Res (including me) find that dressing up your creatu would be very unrealistic and Neopets-like and would ruin Res's originality.
And there has been a glitch for a while that has disabled your pets from being able to die, so you don't have to worry about it for now. However, you should still try to feed your creatu reasonably, and that is how you'll keep your pet from dying later on as well.