That's an excellent question for someone who's just starting to understand chemistry. However, by a freak coincidence you managed to copy an equation that in almost all cases is equal to cursing in a church. Don't sweat it though.
Plusses and minuses in superscript indeed are a representation of the number of electrons a compound or atom is currently carrying. A plus means it's lost an electron (compared to the neutral atom/compound), two plusses means it's lost 2 electrons, etc. The opposite goes for a minus, this means it gained an electron. The process of acquiring or losing electrons is called ionization.
Ionization happens because many atoms (and molecules) in a pure state are rather unstable. Taking iron metal, for example, you know that if you leave something made of iron in wet conditions, it will start to rust. This is simply the formation of iron oxide, in which iron loses electrons (is oxidized) to atmospheric oxygen (which is reduced). Iron oxide has the formula Fe
2O
3, which means that every iron atom has lost 3 electrons, and each oxygen atom has gained 2 electrons.
In the end, when writing chemical equations, not only do atoms need to be balanced out, but charges too (this doesn't mean that your equation as a whole needs to be neutral, it just needs to have the same net charge on each side).
E is something that can mean several things, but in this case I'm going to guess that you mean redox potential. This is a measure of how easily an atom/compound/ion gains or loses one or more electrons (is reduced or oxidized). To put it shortly, any atom, ion or compound will give electrons to any other atom, ion or compound which has a larger or more positive (reduction) potential. Iron, for example, has a low reduction potential, and as such will reduce many compounds with a more positive one, such as oxygen.
Hope this helps.