RobH_en_tn/lev/26/16.md

if you do these things

The phrase "these things" refers to the things listed in Leviticus 26:14-15.

I will inflict terror on you

Here "terror" represents the things that will cause them to be terrified. Alternate translation: "I will send disasters that will terrify you" (See: rc://en/ta/man/translate/figs-metaphor)

will drain away your life

"will slowly take away your life" or "will slowly make you die." It is the diseases and the fever that will do this.

You will plant your seeds for nothing

The phrase "for nothing" means that they would get nothing from their work. Alternate translation: "You will plant your seeds in vain" or "You will plant your seeds, but you will not get anything from them" (See: rc://en/ta/man/translate/figs-idiom)