What is an 'Excess' payment?

The simplest explanation is offered by Finder.com.au:

"An excess or deductible in insurance including travel insurance is the amount you pay towards any claim that you make on your policy. The remaining amount is paid by the insurer up to the limit of the benefit.

The excess will be a set amount stipulated in the 'Policy Wording' ....

Why pay an excess?

When you obtain travel insurance with an excess option, you are assuming part of the risk in return for a lower premium or payment. There are travel insurance options available there that offer zero excess options but this means you are paying more upfront."

Reference: finder.com.au

With Wise Traveller travel cover inclusion you enjoy increased benefit limits across all benefits with the inclusion of a nominal Excess only on Medical Expenses.  All other benefits do not carry an excess.  This also allows the inclusion of a superior level of travel cover within the membership for an annual subscription that is considerably less than most other providers.