How is the concept of a one to one correspondence used in counting?

A one-to-one correspondence is made between the set of number words and the set of things to be counted. This counting with a one-to-one correspondence is called as rote counting.

Example:

To count five blocks, make a one-to-one correspondence between the set of words {“one”, “two”, “three”, “four”, “five”} and the set of blocks.