You pull the front wheels and one side's pads are nearly gone while the other still has plenty of material. Side-to-side wear like this is not normal - healthy front brakes wear evenly. It points to a specific mechanical fault on the worn side. Here is how to find it.
A sticking caliper on the worn side
The most common cause is a caliper on the fast-wearing side that does not release fully - a seized piston or frozen slide pins keeping the pad dragging on the rotor; see caliper won't retract and sticking caliper symptoms. That side does more than its share of braking and wears out quickly, often with a hot wheel and a pull.
A collapsed brake hose
A deteriorated hose on the worn side can trap pressure so that caliper stays partly applied, or restrict flow so it grabs unevenly - see brake hose replacement. It produces the same one-sided wear as a sticking caliper and is easy to overlook because the hose looks fine outside.
Reading the pattern
Also note HOW it wore. If just the inner pad on that side is gone, suspect the piston; if the outer, suspect the slide pins - see reading pad wear patterns. Even side-to-side but tapered wear points to hardware; lopsided side-to-side points to a hydraulic or caliper fault on one corner.
Fix the cause, then replace as a set
Never just slap new pads on - the fault repeats and eats the new pads. Free or replace the sticking caliper or hose first, then fit fresh pads as an axle set with new hardware so both sides wear evenly again.