As a start visually check the brakes pads to see how much friction material (pads) is left. This can be done without removing them. There should be a square shaped groove/slot across the pad in the middle area. If the groove/slot is gone then the pads are worn out. Each pads has its own wear indicator slot.
Sometimes they can make the noise you mention because the pad has developed a tiny, say 1 -2 millimeter high lip right at the out edge of the pad and this can make a noise as the wheel is rotating at slow speeds like 10 -20 kph. This is doing no damage but is just annoying.
To fix this remove the pads. You will be able to feel the lip on the pad with your finger tip or finger nail. Gently sand the edge off (remove the edge/lip on the pad) by taking a piece of not too rough sandpaper and lay it flat on a bench top, table top or concrete floor so that it stays flat. Then gently slide the pad across the sandpaper a few times. 3 - 5 passes should do it. Wipe the pad clean with a clean rag or use some Brake Cleens (aersol can from Canadian Tire or any automotive store). Feel if the lip is gone. If it is, simply reinstall the pads. Check the brake operation in the driveway before you head out onto the road.
Best of luck.
