It is not stopping aging, it is reversing it. You get old because your cells divide just repairing and maintaining the body. Each time one cell divides itself, the copies get a little shorter telomere.
When the telomere is in bad condition, your cells divide slower or even not divide itself.
When this happens your tissues do not repair fast enough, and everything gets a worse condition, your skin, your hair, your brain, your heart.
Restoring telomeres means your cells could start dividing again. At 75 your body will go back to "young adult" 20 years old, without the hair, teeth and whatever you have lost in your life, and the scars, and broken bones soldering, or damaged ligaments that you already have got in your life.
However, lots of animals could grow hair and teeth again so they will probably find a way to make that too.
People will continue dying, but young in their 100s, or in their 20s like today, in things like accidents, wars, terrorist attacks and so on.
People won't die from old age, like most people do today.
Of course this will change the world and will have terrible social consequences.
We will need a better (bigger and cheaper) energy source(fusion) that what we have today to sustain a population that mostly never dies, population and social controls(because old-now young people will have a terrible advantage, experience while being young, and all their accumulated compound wealth) and a way to start exploring other planets and living there.
