Did you know Korean has a bunch of ways to say goodbye?
These are the formal ways to say goodbye and what makes them different:
>>>>> This literally means: Please GO well :) <<<<<
가다 means "to go" (가자, 가지마, etc)
so 가세요 means "please go"
Say it when: You stay, they GO.
>>>>> This literally means: Please STAY well :) <<<<<
계세요 is the polite way to stay "to be"
so this means "please remain/stay well"