People who die are spoken of as if they are going down into the grave. AT: "I will die like those who are in the grave" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Lifting up hands is a symbol of worship. The writer is not worshiping the holy place, but Yahweh who lives in the holy place. (See: [[rc://en/ta/man/translate/translate-symaction]])
Possible meanings are 1) if David wrote this, then this refers to the tent that God told his people to set up so that they could worship him there, or 2) if a person wrote this after the time of David, then the writer is referring to the temple in Jerusalem.