Firstly @Fightingtobepositive please don't Google. Most of what you read up will be worst case scenario.
It is standard practice to have a biopsy done on something suspicious looking. It is only from this that they can see if it is indeed a basal cell, squamous cell etc. A lot of the time, they even come back clear.
Basal cell are pretty common in all honesty. If the histology comes back positive, then the offending cells will be removed. Depending of where and size they can be burned off with liquid nitrogen or cut out.
I first started to have spots burned off as a child. I am very fair and in our lifestyle it is almost impossible to avoid the sun completely. So we go for more regular checks, and anything suspicious looking is zapped away.
I have had over a 100 areas zapped or cut over the years. Only two have ever come back as positive, which were squamous cells, but to be fair I did leave them a bit longer than I should have. They were cut out. The area around is checked again to be sure everything was taken out, and that is that.
He may even find more appearing from now on. As I said previously, the sun damage has already taken place. I do not know how the NHS work for this, but a yearly check up and skin mapping here is the norm post any treatment.
You cannot reverse it, but you can be more aware to prevent over exposure. Also, some sun on your skin is good for you, but you do need to prevent a burn.
Good luck to him, he is doing the right thing in having it tested.