EW is where you're backing the dog/horse to win and also place. So €2 e/w means a total bet of €4, €2 on it to win and €2 on it to place.
The place in horses is usually the top 3. Not sure on greyhounds.
E.G If a horse is 8/1, it gets placed and the race is e/w 1/4 odds. To work out your return you need to get a quarter of 8/1 which will give you your place odds which in this case would be 2/1 so if you had a euro e/w you would get a return of €3.
If the race was 1/5th of the odds you would get a fifth of the 8/1 to get your place odds.