Hi and welcome to TFP
bubbles in the pump basket means there is an air leak somewhere, and air is being sucked in.
The most usual cause of this, is the rubber O ring on the pump basket lid. Usually, applying some slicone based lubricant to the O ring will remedy that problem because it helps the O ring seal off better. Aladdins Magic Lube or some similar lubricant is available at hardware stores, pool stores and big box stores.
Only use silicone or water based lubricant on plumbing O rings. Petroleum ones such as vaseline will make the O ring swell up and not seal off properly.
A rubber mallet is helpful in removing the pump lid if your has ears on it.

or a short 2 x 4. Just tap gently on the ears of the lid and it will unscrew.
Or if you have the big thumb screws on the lid instead of ears, well.. yeah, you might need some pliers to get them loose.
It might also be possible that there is a small leak in one of the plumbing connections on the suction side that causes the bubbles. You can find the leak by spraying some foam shaving cream on the couplings. If there is any small air leak, the foam shaving cream will be sucked in.
If you dont have any shaving cream, you can use a water hose and gently run the water over the connections. WHen you run the water over the air leak, the bubbles in the pump basket will disappear.
Another thing that can cause bubbles is low water level. If you look in the skimmer and see a vortex, then the water level is too low and the vortex is sucking in air.
Hope this helps you in finding the cause of the bubbles