Shellac is a type of clear liquid that is used to make things shiny or to protect them.
Shellac can make people think of old-fashioned furniture or musical instruments.
Examples:
The table is shiny because it has shellac on it.
I will shellac the wood to protect it.
The shellac makes the floor shiny.
I accidentally spilled shellac on the floor and now it's super shiny!
He used so much shellac that the whole room is shining!
The old guitar is shellacked and looks very nice.