A more thorough explanation:

An exhausted vote is a preferential vote in which all the ranked candidates have already been elected or eliminated. This means that the vote no longer counts towards the final outcome of the election.

For example, in a preferential voting system, voters rank their preferred candidates in order. If their first choice is eliminated, their vote is transferred to their second choice. This process continues until all candidates have been either elected or eliminated. If a voter's ballot has no remaining candidates to transfer their vote to, their vote is considered exhausted.

Exhausted votes can have an impact on the final outcome of an election, as they reduce the total number of votes that count towards the winning candidate.