It's probably the capacitor.

Yes, that humming sound means the motor is getting power but can’t start spinning. The most common culprit is a dead start capacitor.

Pool pump motors use a capacitor to give the motor that initial kick to get moving. When it fails, you get the hum—electricity is flowing, but there’s not enough torque to turn the shaft. Sometimes the impeller is just jammed with debris, but more often it’s the capacitor.

Try this first: With the power off, stick a screwdriver or a Allen wrench into the back of the motor shaft (there’s usually a little hole) and try to spin it manually. If it spins free, then power back on, and if it hums again, it’s the capacitor. If it won’t spin at all, the motor bearings are seized—you’re buying a new pump.

Capacitors are cheap ($10–20) and easy to swap. A quick YouTube video shows you how (discharge it first with a screwdriver across the terminals). But if you’re not comfortable with electrical stuff, call a pool guy. One call beats replacing a whole pump because you zapped yourself.

I would not bother calling a repair service for just a capacitor—they’ll charge you $150 for something you can do in ten minutes.