Yes, that's exactly what it does! It prevents STDOUT standard output being echoed to the screen by redirecting it to a nul, non-existing, device >NUL or more precisely 1>NUL. STDERR standard errors being echoed to the screen by redirecting it to a nul, non-existing, device 2>NUL or also 2>&1 meaning the same nul device as the STDOUT was redirected. They can obviously be removed if you wish to see those things echod to the console.