While parsing a string from a grammar using LR parser (bottom-up parser) when we encounter a reduce move(r_{i}) in the parsing table,

1) we pop-off 2*x elements (x grammar symbols and x state symbols) from the stack where x is length of RHS of production rule (denoted by r_{i }in our parsing table)

2) and we push the LHS of the production rule (**which production rule ?** the production rule denoted by r_{i} in our parsing table)

Now the x grammar-symbols we popped-off from the stack is called as HANDLE ...