en_tn/mrk/13/30.md

Truly I say to you

This indicates that the statement that follows is especially important. See how you translated this in Mark 3:28.

will not pass away

This is a polite way to talk about someone dying. Alternate translation: "will not die" or "will not end" (See: rc://en/ta/man/translate/figs-euphemism)

until all of these things

The phrase "these things" refers to the days of tribulation.