Usually: A worn CV joint, usually on the outer end of a driveshaft.
But it can also be: A stone in a wheel trim, or a loose wheel trim itself, which is a two-minute fix.
Clicking when you turn
A clicking noise that only shows up when you turn the wheel, especially at low speed, is usually a worn CV joint. This is more specifically the outer joint on one of the front driveshafts, the part that lets power reach the wheel while it swivels. It wears out from age and mileage, and once the rubber boot around it splits and lets the grease out, the joint starts to click under load.
Before you assume the worst, check the cheap explanation. A stone caught in a wheel trim, or a wheel trim that has come slightly loose, makes a very similar clicking sound and costs nothing to fix once you find it. It's worth two minutes with a flashlight before you plan on a repair bill.
How to tell which one it is
Find an empty parking lot. Roll the windows down, turn the wheel all the way to full lock, and drive slowly in a tight circle, one direction and then the other. A CV joint will click rhythmically, in time with the wheel turning, and it will almost always be worse on full lock than partway. If the clicking speeds up and slows down with your driving speed rather than with the steering angle, that points more toward a wheel bearing or something else entirely. If you can make the noise stop by pulling off the wheel trim and checking for a stone, you've found your answer already.
Is it safe to keep driving
A clicking CV joint is not an emergency by itself. Plenty of people drive on one for weeks. The risk is that a joint that's clicking has usually lost its grease and is wearing fast, and if it fails completely while you're turning, under load, you can lose the ability to steer or drive that wheel at all. It won't happen without warning, but it also won't fix itself. Treat it as something to get looked at soon, not something to ignore all winter.
What the repair involves
If it is the joint, the usual fix is replacing the outer CV joint or the whole driveshaft assembly, depending on what's more practical for that vehicle. It's a few hours of labor, not a same-day walk-in job in most cases, and the cost varies a fair bit by make and model. We'd want to confirm it's actually the joint first, rather than a bearing or a loose trim, since those are cheaper and different jobs entirely. Bring it in and we can check it on the lift and tell you which one you're dealing with before anything gets ordered.