is said that we can bring only items that are 3oz and under is that including the luggage that we check-in?

A: no, the 3oz rule is for carry-on liquids, like lotion, shampoo, sanitizer gel. You can put bigger ones in your luggage, but make sure you wrap it well or it will be all over your clothing. I've heard that sometimes they pop open because of air pressure. Don't bring larger sizes unless you know you really need it--buy what you need at your destination.