Your Realtor can inquire for you with the HOA board or get a copy of the CC&R's for you.
Normally they are used for such things as:
. Outdoor landscaping and maintenance
. Fire Insurance
. Pool maintenance
. exterior Paint and repairs
. Any and all common area maintenance including, walkways, gates, elevators,stairs,tennis courts,
Sometimes basic internet, cable or other utilities are covered
membership in the community Health Club and activities (as with Playa Vista)
Some communities are very active with special events for the residents the HOA covers some of these expenses as well.
HOA when all things considered, is probably close to what you would have to pay yourself over time for maintenance on a house with the same features.