The LG Optimus G Pro's micro USB port uses Slimport. To connect to an HDTV you will need a HDMI cable, and Slimport adapter (sold separately).
Connect your device to the Slimport adapter.
Connect the HDMI cable to your HDTV and Slimport adapter.
You will need to change the input of your HDTV to the correct HDMI input.
Note: Some Slimport adapters are made for specific manufacturers, check that the adapter you purchase is compatible with your device.