en_tn/mat/24/40.md

Connecting Statement:

Jesus begins to tell his disciples to be ready for his return.

Then

This is when the Son of Man comes.

one will be taken, and one will be left

Possible meanings are 1) the Son of Man will take one away to heaven and will leave the other on earth for punishment or 2) the angels will take one away for punishment and leave the other for blessing. (See: rc://en/ta/man/translate/figs-activepassive)

mill

a tool for grinding

Therefore

"Because of what I have told you"

be on your guard

"pay attention"