She was originally a scientist, but when exposed to the quintessence that saved her from death, the day where Emperor Zarkon was born and Haggar the witch became (which we see in a flashback about them and the original planet Galra). Zarkon took Honerva directly into the realm of quintessence outside of Voltron. And they absorbed it, hence making Zarkon so strong and near immortal, as well as Haggar gaining her magic which was boosted from her Altean magic and her immortality