It is my understanding that all the beaches in Barbados are public beaches. However, the hotels provide chairs and (at some) even refreshments can be ordered. If you are not a hotel guest it is possible to sort of sneak onto 'their' beach, however I never found it necessary. There are so many wonderful beaches from which to choose!!
There is a nightclub/restaurant named The Boatyard located in or right next to Holetown. During the day you can relax on the beach and/or eat at the restaurant. There are all sorts of 'water toys' right off the beach that you can enjoy (trampolines etc.). The Boatyard is also the location from with the Jolly Roger departs & returns.
At night The Boatyard becomes a fun-filled nightclub! Hope this helps!
