It is a name of German women. It is one of the many variants of Juana which means "Full of grace", Juana is of biblical origin origin. Other variants are Joan, Johanna, Joana, Jovanna, Giovanna, Yohanna or Yovanna.
Jhoana, or best Johana, is a feminine name that is believed to be of Germanic origin. Juana is could have derived from the proper name.