"M2" on a keyboard can refer to different things depending on the context. Here are some possible meanings:

1. Mouse buttons: In the context of the GK61 keyboard, "M1", "M2", and "M3" likely refer to the left, right, and wheel click buttons of a mouse.
2. Square meter symbol: "m2" is the abbreviation for square meters, and you can type the square meter symbol "m²" on a keyboard using different methods depending on the software and operating system you are using. For example, in Microsoft Word, you can type "m2", highlight the "2", and then press and hold Ctrl and Shift while pressing the "+" key to superscript the "2" and create the "m²" symbol. Alternatively, you can use the numeric keypad to type the Alt code "0178" while holding down the Alt key to create the superscript "2" symbol.
3. A keyboard model: "M2" can also refer to a specific keyboard model, such as the MonsGeek M2, which is a 1800 compact QMK and south-facing aluminum barebone keyboard.

In summary, "M2" on a keyboard can mean different things depending on the context, such as mouse buttons, the square meter symbol, or a specific keyboard model.