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

"Pass away" is a polite way of saying "die." Alternate translation: "will not die" or "will not end" (See: rc://en/ta/man/jit/figs-euphemism)

until all of these things

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