The module has several iterations with slight hardware differences: Bluetooth audio - Raspberry Pi Official Magazine

: Alternative stereo output terminals (Left, Right, and Common Ground) for internal wiring to an amplifier board.

: Look for the official website of the company that produces VHM 314. If you know the manufacturer, this is usually the best place to start. Companies like Hextool, Sumitomo, or other hardmetal producers often have datasheets available for download.