jQuery.each(function(index, value){}); What is value?

I am learning jQuery from a book called Head First jQuery. The book is very easy to learn from. The point is, there is an .each() function(included in image which I scanned from the ) which has a function() parameter. The function() parameters are index and value. The index is explained on the page, but what about the value? And also, since it is an anonymous function(which cannot be reused) how does it take any parameters?