Hibernate Spatial is a generic extension to Hibernate for handling geographic data. It is generic in the sense that it works in the same way across different databases.
Hibernate Spatial allows you to deal with geographic data in a standardized way, whatever database that you use (as long as a Spatial Dialect Provider exists for it). In other words, it abstracts away from the specific way your database supports geographic data, and provides a standardized, cross-database interface to geographic data storage and query functions.
Hibernate Spatial supports most of the functions of the OGC Simple Feature Specification.