This is the 89th most frequent Catalan word.
casa
House
Here, 'casa' is used as a noun meaning 'house', referring to a physical building where people live.
La casa és molt gran.
The house is very big.
In this sentence, 'casa' is used once again as a noun but within the context of a location or destination.
El gat està entrant a la casa.
The cat is entering the house.
Here, 'casa' is used idiomatically to mean 'home', indicating one's personal living space without mentioning a specific building.