What does las cinco y cuarto de la mean?

"Las cinco y cuarto de la" is grammatically incorrect. The correct phrase would be "Las cinco y cuarto".

Here's what it means:

* Las cinco: Five o'clock

* y cuarto: And a quarter (of an hour)

So, "Las cinco y cuarto" means 5:15 AM (assuming it's in the morning) or 5:15 PM (assuming it's in the afternoon or evening).

It's important to note that in Spanish, "la" is not used with time expressions like "las cinco".