These are a custom spelling of xe/xem/xyr pronouns.

To pronounce these pronouns, use a Zee sound for the X.
Full phonetic pronunciation would be: zee / zim / zee-er / zee-ers.

Examples of xe/xim/xier pronouns:

Xe went to the park.I went with xim.Xe brought xier frisbee.At least I think it was xiers.Xe threw the frisbee to xierself.

These example sentences are copied from Pronoun Island.
Pronoun island has been rehosted, clicking on this link will take you to the new Pronoun Island website.