Things that are dry lack moisture. A desert or a dessert can be dry. If your eyes are dry, you’ve stopped crying. It’s also a flavor that means the opposite of sweet.
The Sahara Desert and crumbly chocolate cake are both dry. Dry is also a verb — when you paint your kitchen, you have to wait for the first coat to dry before you can add another. If someone says you have a dry sense of humor, they mean that you have a subtle style, keeping a straight face even when you say something outrageous.