This is a Yucca plant, also called lily palm, Spanish dagger, mound lily and Adam's needle.  It is native to the Southeast US.  Once established, it requires little care:  light pruning (removing dead, damaged leaves and spend flower stalks); watering every week to 10 days (depending on weather and how quickly it dries out - more critical in a flower pot); feeding with half-strength 10-10-10 fertilizer in the spring before new growth starts, and watching for scale insects, aphids and mealybugs (use insecticidal soap if necessary).  The plant will form offshoots which can be separated and  replanted.

The spent flower stalk should be removed after the flowers are finished.  Use a clean, long-handled hefty pair of loppers and water well afterwards.

Cease watering when fall rains start, and resume when the weather dries out in the spring.

This article, Adam's Needle, gives more information.