A storey is a level of a building. If a building has many storeys, it is very tall.
Buildings with many storeys are often found in big cities and are used for offices or apartments.
Examples:
The building has 10 storeys.
The storey where the library is has lots of books.
I live on the top storey of the building.
The tallest building has 100 storeys!
The storey with the restaurant is on the first floor.
The storey with the pool is my favorite.