I see that someone posted a link for you in your other thread with regards to common gun abbreviations.
With regards to a handgun, you will get a lot of different advice. I normally suggest that new handgun shooters consider a double action revolver like a Smith & Wesson model 10 for example. The .38 Special caliber is easy to shoot, and works well for defense. The model 10 is a great choice for home defense but probably a little big for most people to carry concealed. Once you master the double action trigger, you can learn to shoot pretty much anything else.
If you are set on getting a semi-auto pistol, I recommend a weapon chambered for the 9mm round. I personally like Glocks, but there are many other great choices on the market today.
Good luck and feel free to ask lots of questions.