RAM is short for random access memory
RAM is volatile and only stores open applications,the operating system and the graphical user inteface
It is not permanent storage and cant be saved to, it's wiped every time you power off your computer because all programs are closed.
It is measured in gigabytes and 8 gigabytes is the usual amount nowdays
There is a faster option available; cache which works faster but is much more expensive
The creator of this guide has not included tools