What is the meaning of Overall?

Generally; with everything considered.

A garment worn over other clothing to protect it; a coverall or boiler suit. A garment, for manual labor or for casual wear, often made of a single piece of fabric, with long legs and a bib upper, supported from the shoulders with straps, and having several large pockets and loops for carrying tools.

A garment, worn for manual labor, with an integral covering extending to the chest, supported by straps.