Q: How big is a guitar?
A: There are different shapes and sizes. The guitar should feel right for you. You shouldn't have to struggle to get your hands around it.
Q: Acoustic guitar or electric?
A: Acoustic, I'd say.
Q: Why? And what the heck is an acoustic guitar?
A: An acoustic guitar is a classic guitar. It does not need any electrical power or fancy equipment. It has a body that amplifies the vibrations of the strings, and you can feel it vibrate (or dance) in your hands. Quite a satisfying feeling.
Q: How many strings does a guitar have?
A: Six. There are usually six strings.
Q: Is there a problem if my guitar has less strings?
A: Yes. If you have inherited the guitar from someone else or your guitar just snapped a string or two, you have to replace them. Just buy a set of strings and ask someone with experience to replace them for you. Or do it yourself if you don't have two left hands (a pretty good way to tell, actually). Anyhow. If you have less than six strings on your guitar you ain't gonna be able to play it (even if your grandpa's name was Jimi Hendrix).