Here are a selection of the most popular bet types and what they mean.

A WIN BET:
A win bet is what it says on the tin. You pick a team/player and bet on them to win.
You will usually see this set out as followes
1   x   2
1 is home team   x is for the draw   2 is for the away team

LAY:
If you want to make money from gambling then this really is the way to do it.
A lay is basically you being a bookmaker. You would perform this type of bet on the betting exchanges.
When you lay you are saying that an event will not happen. So if you like to bet on the horses and you think a paticular horse is a donkey and has no chance, then you can lay that horse. What you are doing when you lay is allowing somebody to bet with you like bookmakers do. So you would offer your odds and the amount you wish to accept as a bet from ohter people. Then somebody can come along and accept those odds and make there bet.
If you were right and your horse really was a donkey and does not win you win the stake money that you entrerd. However if the Donkey really was a Stallion and wins you must payout the stake X Odds. So if you accepted a bet of £10 at odds 3.0 (2/1) you would payout £20.
Now as there can only be one winner of an event, there are going to be many losers. The odds are in your favour.
For more deatiled explanation of the exchanges CLICK HERE

EACH WAY:
An each way bet comprises two separate bets. One bet is on the selection to win, and the other is on the selection to be placed. For example, a customer placing each way is betting on win, and or a place, total stake The number of places and available odds on offer will be by the relevant bookmaker.

CORRECT SCORE:
Again exactly what it says on the tin.
You place a bet on the exact score. This is a difficult bet to get right, but if you do get it right it will usually pay very well

FIRST/LAST/ANYTIME GOALSCORER
Do you think the star player is so on fire he will score with every touch, then this is the bet for you. If your man scores first or last, whichever you put your money on, then you are in for very good returns.
One thing to think about though, if you do this type of bet every week it may be an idea to look at high scoring midfielders or defenders (Lampard/Gerrard/Lescott) these guys get in the goals for there teams and over a season may provide you with bigger returns over the season than placing your money on lets say Rooney who has Ronaldo/Tevez/Scholes also vying for the goals.

HALF TIME/FULL TIME:
Do you think that it is going to be a tight game, with possibly one team wareing the other down at late into the second half. Or do you think that a team will massacre their opponents. Then this is the bet for you.
You are picking the result of each half. However to win the bet you must correctly pick the result for both halfs. If you only get one right, you lose. However get it right and you are in the money.

eg  Man Utd V Chelsea. Very tight game with Utd just knicking it at the end you would bet on the following
Draw/Man Utd.
That means first half draw and Utd going on to win.

Other examples.
Draw/Draw:            Both halvs are draws
Man Utd/Man Utd     Man Utd lead in the first half and go onto win the game
Man Utd/Chelsea      Man Utd win the first half, however chelsea go on to win the game in the second half
Man Utd/Draw         Man Utd lead after the first half, but the game ends in a draw.

WINNER WITHOUT TOP 4
Do you think your team is the best of the rest. Then this is the bet for you. Basically you are betting on your team finishing 5th in the league, or as the bet is worded first if you discount the top 4. If your team finish anywhere in the top 5 then you win your bet as long as anouther team outside the so called top 4 (Liverpool/Utd/Chelsea/Arsenal) dont finish above you.
The best teams to think of here will be teams such as Everton/Spurs/Newcastle.

TOTAL GOALS:
Again what it says on the tin. If you think 3 goals will be scored in the game then have a bet.
However any less or any more than 3 goals and you lose.

There are many more types of bets but that was a selection of the most popular ones in todays markets.