Your bones have two kinds of cells that do all the work to remodel your skeleton as needed. Osteoclasts break down old bone and deliver it into your bloodstream (resorption), and osteoblasts build your bone where it needs to be reinforced (ossification). Bones are reinforced through osseointegration, where they are used the most. For your jawbone, when you chew and bite, the force you exert through your teeth into your jaws sends signals to osteoblasts to keep that bone strong.
After your tooth extraction, your jawbone will no longer receive stimuli where your tooth once was, osteoclasts will begin to break down your jawbone, and osteoblasts will no longer prioritize rebuilding the bone structure there. New bone will still form, but at a slower rate than the bone that is being destroyed. This can cause your other teeth to shift and can create complications if you decide to get a dental implant in the future.