en_tn_condensed/luk/21/06.md

these things that you see

This refers to the beautiful temple and its decorations.

the days will come when

"there will be a time when" or "someday"

not one stone will be left on another which will not be torn down

"every stone will be removed from its place and torn down" or "not one stone will be left on another. Enemies will tear down every stone." The temple was made of stones, but enemies would come and destroy it.