Something related to a king or queen, like a royal crown or a royal palace.
Royal things are often thought of as very special, important, and fancy.
Examples:
The royal family lives in the royal palace.
She wore a royal crown on her head.
The royal robe was very fancy.
I want to live in a royal palace with a big garden.
The royal banquet had lots of delicious food.
The royal carriage was pulled by four horses.