In South Carolina a homeowners assessment is paid by property owners to their subdivision's homeowner association and is not a governmental entity. Before you buy a property you should always review the recorded covenants to see what you are getting into and what all of the common property is. Typically the amount of the initial assessment is spelled out along with rules on maximum rate increases.
These assessments cover the costs of managing and maintaining common properties - examples of the types of expenses are landscaping, repairs and maintenance to road access gates, the professional management company's fee, reserve funding for future capital expenses, etc. Some subdivisions have private roads and others have public ones. If your roads are private, there will be a line item in the budget to repair these and reserve funding to repave at a later date.
Also, don't be surprised if the developer has reserved the right to control the association until a substantial build out has occurred. This in itself is not a bad thing - they normally want to ensure that the property is maintained to a high degree until they are substantially sold out. Also, until a certain amount of properties are sold, the developer will frequently subsidize the association.