In French, one of the few words I actually remember, "jolie" means "pretty" or "nice". I'm guessing that might be what whoever named this island was aiming for. Although, given the way they spelled it, possibly the last name of someone.
Let me take you on a tour, starting on a sunny day when I walked past the island entrance and ending with today's cloudy photo trip (click to enlarge):
Cross the wooden bridge over the bay
One of the walking paths on the island
Even a play area for the kids
A wooden pathway on the edge of the water circumnavigates the island
The bridge as viewed from the island
Leaving the island
There are also picnic tables and grills on the island (and "facilities") so it wouldn't be hard to spend a whole afernoon exploring, playing with the kids, cooking out, reading and listening to the birds.