"You are like salt for the people of the world" or "As salt is for food, you are for the world." This can mean 1) "Just as salt makes food good, you must influence the people of the world so that they will be good" or 2) "Just as salt preserves food, so you will keep people from becoming totally corrupt." (See: [[rc://en/ta/man/translate/figs-metaphor]]).
This can mean 1) "if the salt has lost its power to do things that salt does" (as in UDB) or 2) "if the salt has lost its flavor."
## how can it be made salty again? ##
"How can it be made useful again?" or "There is no way for it to become useful again." (See: [[rc://en/ta/man/translate/figs-rquestion]])
## except to be thrown out and trampled under by people's feet ##
"The only thing it is good for is to be thrown out on the road where people walk"
## You are the light of the world ##
"You are like light for the people of the world"
## A city set on a hill cannot be concealed ##
"The lights of a city on a hill cannot be hidden at night" or "Everyone sees the lights of a city on a hill" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-activepassive]])