後の + [noun]
後 + counter (without の; "~ more / ~ left")
The expression 後(の) + Noun is used to refer to what remains, what is left, or the rest of something. It can describe remaining time, remaining items, remaining people, or remaining tasks. The particle の connects あと後 to the following noun as a modifier.
When you want to talk about what is left of something, 後の + Noun expresses "the remaining ~" or "the rest of ~."
後 + counter (without の) is used to express how much time, distance, or quantity is left before something is completed. In this usage, it translates to "~ more" or "~ left" or "~ to go."
後の can also mean "other" or "else" when contrasting one thing with everything remaining.