Hi, recently bought a 2013 Mirage LS. I’m a middle aged female who doesn’t really know much about transmission.

Could someone explain to me in layman’s terms what this CVT thing is all about? My understanding is that the engine is constantly going smoothly from 1 to 10 and back, as opposed to the normal auto transmission that clearly goes from 1st to 2nd, to 3rd... etc.
Am I close?

Also, what is this “breaking” (B) option below the “drive” (D) gear?
In the book it said it’s for when you need engine breaking, like in a traffic jam or something?
Which situations would it be used in? Why? Is it fuel efficient? Can it be used on highways at 110kmph?