This is the name of the site.
Tagline : "For each word you get right, we donate 10 grains of rice through the United Nations to end world hunger"
What you have to do is guess the meanings of the given words and for each correct guess, 10 grains of rice are donated.
The words are not that tough (atleast till level 40). So, friends, go ahead and donate as much as you can, while improving your vocabulary power. Please do this every day. I do. Lets make this minuscule contribution ourselves each day to bring an end to world hunger.
P.S. Imagine how little 10 grains is. So donate much much more. And, pass the word