Sometimes I find that explaining computer stuff in terms of other things in their life makes them understandable. With that in mind, here are my explanations:
PC
It means personal computer. Either a Desktop or a Notebook. It's a computer that is used by ordinary people and businesses to do things. In the past many of these things used to be done with physical items, like mailing a letter, can now be done electronically on a PC. PCs like people have a language they use or "speak". Some speak "Windows", some speak "Mac OS X" and some speak "Linux".
Mac
A Mac is also a PC made by Apple Inc.. It's a personal computer that uses Mac OS X
Hardware
Are the mechanical parts of a PC.
Software
This can be either the OS, the language the computer speaks, or the programs, the instructions or recipes that the computer use to do things.
RAM
This is like your car, you get in it, others get in it, you put things in it and it will take you to and from places. Only so many people and/or things can fit in it at one time. If you have more people and/or things than will fit in it at one time you'll have to make multiple trips back and forth to get it all done. If you had a bigger vehicle like a van or a truck you could make few trips to accomplish the same thing. RAM works like your car for getting software and information back and forth for things that you are having the computer do.
Operating System
The language the computer speaks,
Internet
Are computers all over the world connected to one another through Internet Service Providers. Internet Service Providers are like the phone company, heck some of them even are the phone company, and it allows all of us all over the world with our computer to connect to one another and share things and do things on the internet.
Webpage
It can be a lot of things, but basically it's an electronic version of a newspaper or a magazine.
Flashdrive
A piece of computer hardware that acts as bag or briefcase to hold/carry electronic information like software, photos, music, etc.
iPad
A small computer, the size of a magazine that you can use to do many of the same things that you do on a full size computer.
Email
An electronic version of physical mail. Just like writing and sending a letter, or getting a bill through the postal service, except it's all done electronically with a computer.
Desktop
This is usually the first thing you see when you turn on a computer. Its an electronic representation of the foyer or vestibule to your house. When you come into your house you'll be in the foyer and in front of you you can see places you can go. You could go into your living room and pickup your paper and read it, you could go into your closet and get out your umbrella, or you could go to your family room and watch TV, your computer's desktop is like the foyer, it gives you access to other things on your computer.
understand and learn.
