After is a preposition meaning "later in time" or "behind in space." After many hours of dancing, you'll be sweaty and hungry.
You can use this word in the context of time: "Meet me after dinner and we'll take a walk." After can also refer to space: "My street is after the first stoplight." Finally, after can be an adverb: "Jack and Jill went up the hill to fetch a pail of water. Jack fell down and broke his crown, and Jill came tumbling after." If you like ships, you'll recognize the relationship of after to aft, which means the rear part of the ship.