This isn't the end of the script. It's the end of the subroutine, kind of like a function. It starts with the label `:findFirefox` and ends with `goto :eof` Toward the top of the script there is a line `call :findFirefox` that executes this subroutine if SLIMERJSLAUNCHER is not an existing path.

`goto :eof` is like `return` There is a subroutine for the `:helpMessage` too. The script actually runs from the top and exits around the middle. The bottom half are just functions that might get called. The `goto :eof` just before the label `:helpMessage` is the point in the code where this batch file returns control to its caller.