If your desired language is not available in the menu, you must download a language pack (often found on community forums like Evo-Web) and install it manually:

Modders added full commentary for:

Markus shook his head slowly. He pointed at the television. The CRT glass wasn't reflecting the basement anymore. It was reflecting a stadium. An empty one. And in the center circle, two player models stood motionless: a pixelated Henry and a pixelated Bergkamp. They were facing away from each other. Between them, on the turf, lay a small silver disc.

A complete language pack for PES 6 PC usually contains: