Here is a list of symbols that normally appear on the status bar of a mobile phone and what they mean;
G - GPRS or 2G. This is the slowest form of internet data speed for mobiles.
E - Edge or 2.5G. This is the next highest speed of mobile internet data above GPRS.
H - HSDPA or 3G. Most phones display it as 3G However there are some models that display it as H or occasionally HSDPA
H+ - HSDPA+ or 3.5G. Again most phones will display it as H+ or occasionally HSDPA+
4G - a.k.a LTE, currently the highest form of speed for mobile internet