The plant appears to be an Agave of which there are many species and cultivars but all are monocarpic, meaning once it blooms the “mother” plant will die. Usually there are offsets or “babies” of the mother plant that will take its place. Many do take over 20 years to bloom and the spectacular process may take months. The flowering is the natural culmination of its existence. Once the bloom has dried, many people keep it as a cut dried flower if they have the room! Outdoors provide excellent drainage, full sun and water sparingly, only when soil feels dry to the touch. Prized for its tapered, pointed leaves. Indoors, provide the brightest, indirect light possible. At this stage could also be another Yucca, but we think it is an Agave.