This continues the prophecy about the people of Moab. God describes events that will happen in the future as if it is happening in the present. (See: [Isaiah 15:1](../15/01.md))
The phrase "my heart" refers to Yahweh. He compares the sadness he feels to the sound of a sad song played on a harp. (See: [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-simile]])