If you mean: "can I get the sound of my electric guitar to be amplified so that I can hear it out of the speaker?"
Well, then yes. Any 1/4 or RCA line input on it should do fine.
If however, you mean: "can I plug my electric guitar straight into this stereo, and have what comes out sound anything like a guitar amp?"
Well, then the answer is NO, NO, NO, FOR THE LOVE OF GOD NO!!!
Let me explain. A stereo/P.A. system is designed to impart as little "color" to the sound as possible. Its amp and speakers are desiqned to reproduce as much of the lows and highs as possible in the music source, with as little distortion as possible.
Well if a stereo is the "family minivan" of sound reproduction, then a guitar amp is the "Ferrari Racer". They're designed with an almost polar opposite set of priorities. For starters, the amp and speakers are designed to drastically limit the frequency range that comes out (notice that you never see horns or tweeters on electric guitar amps?). Why? Because all those brillliant highs and boomy lows sound absolutely, obnoxiously, painfully, horrible sounding when you're amplifying an electric guitar, especially when overdriving or distorting the amp. Which brings us to the second difference. All of the things that a stereo system tries to avoid (i.e. distortion, coloration, etc...) are the things a guitar amp tries to enhance. Why? Because magnetic pickups in electric guitars produce the most dull, sterile, pathetic, nonmusical sound imaginable by themselves. And its the guitar amp's job to add coloration, distortion, etc..
So what can you do? Well here's a couple of options.
1. Break down and buy yourself a guitar amp. Even a super-cheap used one will sound better than running through your stereo.
2. If you have your heart set on using your stereo, then purchase a pre-amp that has cabinet emulation on it. Tech-21 Sansamp, Hughs & Ketner, Rocktron, or even an old Alesis Quadraverb GT would do. Run your guitar into that, then out of it into your stereo.
The second method would make it tolerable sounding, but understand, its like putting "racing slicks" on a "mini-van".
Hope that helps