What Does Exit Code Mean?
An exit code or exit status is a number that is returned by an executable to show whether it was successful. This is also sometimes called a return code, or in some cases, an error code, although the terminology here may be slightly different.
Techopedia Explains Exit Code
The simple explanation for an exit code is that the executable program is programmed to return a whole number that shows whether it was successfully executed. In general, zero is usually the signal for successful execution, and numbers from 1-255 represent various negative outcomes or problems.