Complex sentence: Under STV, an elector's vote is initially allocated to his or her most preferred candidate, and then, after candidates have been either elected or eliminated, any surplus or unused votes are transferred according to the voter's stated preferences.
Split into simpler sentences: Under STV, an elector's vote is initially allocated to his or her most preferred candidate. After candidates have been either elected or eliminated, any surplus or unused votes are transferred to another according to the voter's stated preferences.