Complex sentence: The "Spirit" Class is a class of cruise ships built at the Helsinki New Shipyard (now STX Europe) in Helsinki, Finland for Carnival Cruise Lines and Costa Cruises (both subsidiaries of the Carnival Corporation).
Split into simpler sentences: The "Spirit" class is a class of cruise ships built at the Helsinki New Shipyard (now STX Europe) in Helsinki, Finland. The class are operated by Carnival Cruise Lines and Costa Cruises (both subsidiaries of the Carnival Corporation).