# You are the light of the world

This means Jesus's followers bring the message of God's truth to all the people who do not know God. Alternate translation: "You are like a light for the people of the world" 

# A city set on a hill cannot be hidden

At night when it is dark, people can see the city lights shining. Alternate translation: "No one can hide the lights that shine from a city on a hill" or "Everyone sees the lights of a city on a hill"