After has 7 different meanings across 4 categories:
Later; second (of two); next, following, subsequent
"After finishing his homework, he went outside to play."
In plain English: After describes something that comes later than another event or time period.
"The after effects of the storm made everyone feel tired for days."
happening at a time subsequent to a reference time
"he apologized subsequently"
"he's going to the store but he'll be back here later"
"it didn't happen until afterward"
"two hours after that"
Behind; later in time; following.
"She placed the book after the magazine on the shelf, so it would be behind the other item when opened from left to right."
In plain English: After means later than something else happens, usually coming right after it finishes.
"She arrived after him yesterday morning."
Subsequently to; following in time; later than.
"She finished her homework after dinner."
Signifies that the action of the clause it starts takes place before the action of the other clause.
"After he finished his homework, he went outside to play."
The word "after" comes from Old English and originally meant "further behind." Its roots trace back to ancient languages where it described something that was further away.