Jesus was speaking of himself in the third person. This could be translated in the first person as "when I come in my own glory." (See: [[rc://en/ta/man/translate/figs-123person]])
## some of them who are standing here ##
Here Jesus was referring to some of the people he was speaking to. This could be translated as "some of you standing here now" (UDB).
## will not taste death until they see the kingdom of God ##
This could be translated as "will see the kingdom of God before they die."
## will not taste death ##
"will not experience death" or "will not die"
## until they see the kingdom of God ##
Depending on how you translate "some of them," you could also translate this as "until you see the kingdom of God."