Is $\le$ a binary operation? I am a little confused with $\le$. Is it a binary operation?
I know the definition of binary operation that is any function from $A×A \rightarrow A$ and $A$ non empty.
Kindly help me to understand the concept.

A binary operation on a set $A$ is a function $A \times A \to A$.  You need to be able to plug any elements of $A$ into the function and get an element of $A$ back.  Addition on the naturals is a binary operation.  You can take any two naturals, add them, and get a natural as the result.  
A relation on $A$ is a set of ordered pairs that is a subset of $A \times A$.  It just tells you which pairs are related in this way.  $\le$ is a relation on the naturals.  For some pairs of naturals $(x,y), x \le y$.  For some, not.  Those pairs where $x \le y$ are members of the relation.  Another relation on the naturals is $x|y$, where $x$ is related to $y$ if $x$ divides $y$.
