Here "it" refers to the part in the wall that is about to fall. The part in the wall is a metaphor that represents the people of Judah and their sin mentioned in [Isaiah 30:12-13](./12.md). (See: [[rc://en/ta/man/jit/figs-metaphor]])
This simile means that the piece of wall will break as quickly and completely as a clay jar that falls to the ground. (See: [[rc://en/ta/man/jit/figs-simile]])
This can be stated in active form. Alternate translation: "no one will be able to find" or "there will not be" (See: [[rc://en/ta/man/jit/figs-activepassive]])