What does this code line means ? Name= (string)item.Element("Name"), ?

Name= (string)item.Element("Name")Doesn't declare any variables - it use the already declared Name and puts a value into it.

Exactly what the item.Element("Name") part does is open: without knowing what type item is it could be anything, but the most likely is that it's a generic method that returns an object from a store of some form, using "Name" as the index to locate exactly what item you want to fetch. The (string) part casts that object to a string (if it can, it will fail and throw and exception if it can't) so that the compiler will be happy stroign the value into a string variable called Name

string Name = item.Element("Name");

Does declare the Name variable, and will probably give a compilation error if the Element method does not return a string type.

Your other two lines do very similar things, but this time casting the value to a integer instead of a string.

This is basic stuff: you really need to go back in your notes and review the language from the beginning if you don't understand this too well.