How can I wire this square Pot?
That's a multi-section variable and semi-fixed (trimmer) capacitor out of a radio.
Here is pretty good photo of a similar vintage part (from here):


Typically one variable section would be  used for the AM band and one section for the FM band.
You can't practically use  it directly to control an LED or speaker volume, but you might be able to use it as an input to an MCU by making an oscillator with it and counting the frequency.