True Counting
So the running count (RC) tells you that for the rest of the shoe, on average how many more high cards than low cards there are. When you divide by the number of decks left (converting the RC to a true count, TC), you're checking how many more high cards than low cards there are per deck. So just because there are 20 more high cards left in the shoe, is it the same if those 20 cards are spread out over 6 decks or 2 decks? The answer is no, which is why people prefer TC'ing.
Balanced Counts:
Well, some counts can better identify advantageous situations. But mostly, people use balanced because it's easy to divide by the # of decks left, and see if you're >0.
Unbalanced Counts:
An unbalanced count means that when you go through an entire deck, the final RC isn't 0. I'll use Red 7 as an example. After you go through each deck in a 6 deck shoe, you know what the expected count is. So after 1 deck in, it should be Initial Running Count (IRC) + 2. After 2 decks in, it should be IRC + 4. After 3 decks, it should be IRC + 6, ad infinitum. So for 6 decks, you set the IRC at -12, and at the very end of the entire shoe it would be +0. However, when it starts climbing to +0 before the end of the shoe, you essentially are above the expected count, and you know good cards are coming!
I hope that helps you understand. Remember, TC vs RC is not the same as Balanced vs Unbalanced.
