This rate is the rate that Westpac Banking Corporation will convert foreign currency received by you via a telegraphic transfer from another bank (either in Australia or overseas).
Example - you have received some funds as a gift from a relative in the United States, and they have sent this money to you as U.S. dollars.
The inward telegraphic transfer rate is the rate at which these U.S. dollars will be converted into Australian dollars for your use.