What Is a Bit, and Why Are Some 32 and Others 64?

Gary can you please explain to me, or point me towards a video that will explain the difference between a “32 bit”, and a “64 bit”…”something”?
What is a bit? what is 32 & 64.
These two things keep popping up in my life and I figure better to learn them, than to avoid this any longer. Which is what I’ve been doing.
This morning I received a link for a bundle of free macros for Affinity Photo for HDR. But, it said this is for 32 bit only….no idea what that means.
—–
Greg