"x >> 1" divides x by 2, so it follows that "x >> 2" divides x by four, and "x >> 3" divides x by eight.

Now, 2 = 2^{1}, 4 = 2^{2} and 8 = 2^{3}.

You could write "x >> 3" as " ((x >> 1) >> 1) >> 1", with each successive operator halving thing previous result

Can you see where this is going?

(This isn't an "Arduino" operator, it's a C/C++ operator)