The %~dp0 (that’s a zero) variable when referenced within a Windows batch file will expand to the drive letter and path of that batch file.
The variables %0-%9 refer to the command line parameters of the batch file. %1-%9 refer to command line arguments after the batch file name. %0 refers to the batch file itself.
If you follow the percent character (%) with a tilde character (~), you can insert a modifier(s) before the parameter number to alter the way the variable is expanded. The d modifier expands to the drive letter and the p modifier expands to the path of the parameter.
Example: Let’s say you have a directory on C: called bat_files, and in that directory is a file called example.bat. In this case, %~dp0 (combining the d and p modifiers) will expand to C:\bat_files\.
Check out this Microsoft article for a full explanation.
Also, check out this forum thread.