To be superlying means to be lying on top of something else.
Superlying is usually about being on top of something. It's like being the boss of something.
Examples:
The book is superlying on the table.
The blanket is superlying on the bed.
The cat is superlying on the chair.
The clouds are superlying on the mountain.
The big tree is superlying on the small flowers.
The superhero is superlying on the building!