There are three main types of 6 string guitar that you will encounter. These are the Classical or Nylon Stringed instruments, Steel Stringed instruments and and the Electric Guitar
Chances are that if you have asked someone if you can use their guitar for a while, it would probably be an old classical or nylon guitar or maybe a steel string guitar.
Nylon guitars is excellent to learn on because they are easy on the fingers. Steel stringed guitar is very tough on the fingers initially and not good for beginners. Electric guitars require things like leads, amps, speakers and power and also have a very narrow neck and the fretboard is much narrower.
With nylon or acoustic (guitars that produce their own sound via an internal sound box) you only need your fingers to play the instrument, or at most, a pick.
When you are learning it is better to play on a nylon guitar that isn’t going to be too loud (unlike an electric guitar); only loud enough so your ears can hear yourself play and also your initial errors. Due to this you don’t disturb your family or the neighbours when you practice.
I therefore highly recommend that you stick with a simple nylon guitar or at least until you are more accomplished in basic technique for the instrument i.e. chords, strumming and fingerpicking. After you get your skills up to a reasonable level you can make other decisions about different guitars you want to play or other styles of playing you want to investigate or follow. By then you will have built a good ear and have the experience and confidence (competence) to make the best decision.