The "heart" represents a person's emotions. This speaks of a person being discouraged as if their emotions were sick. AT: "Because of this we are discouraged" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-metaphor]])
This means that they have a hard time seeing because they are crying. AT: "and we can hardly see because our eyes are full of tears" (See: [[rc://en/ta/man/translate/figs-explicit]])
# for Mount Zion lies desolate
Here "Mount Zion" refers to Jerusalem. The phrase "lies desolate" means that no one lives there.