what does cin.get function do??
Depends on how you use it. Here is a link with an example:
It gets one character from the keyboard.
Always one? This line is from the cplusplus.com example. I've never used it to get more than one myself:
Yes it can be used to extract more than one caracter. I always use cin.getline( ... ) for that since it has more options, you can tell it what terminating character to use.