What does this question even mean?
I don’t understand this question as well! Aren’t all buttons on a gamepad analogue?
As wikipedia says about “Analogue Stick”: While digital sticks rely on single electrical connections for movement (using internal digital electrical contacts for up, down, left and right), analog sticks use continuous electrical activity running through potentiometers. So if you think for example about a racing game where the more you press the trigger the more speed you give to your car, it should give you the idea.
Analog means that it can give more than 2 states, pressed and not pressed.
Shoulder buttons are analogic, but also is the stick, and in some cases the buttons. This one tripped me.