If something is messy, it is not clean and is untidy.
Messy things can make people feel disorganized or uncomfortable.
Examples:
The room is messy with toys everywhere.
She has messy hair after playing outside.
The kitchen is always messy after we cook.
My little brother's room is so messy, you can't even see the floor!
The art project was so messy, paint got everywhere.
Eating spaghetti can be messy if you don't use a napkin.