Hurston means that Teacake taught Janie to appreciate and respect the fact that she was a woman and the things that come along with that.
Janie was oppressed when she was forced to be with Logan at the beginning of the book. He felt she was spoiled and lazy, and he thought she needed to put in some manual labor. He had a view of how he expected her to be, and he got angry when she did not live up to it. Janie didn't love Logan and felt she could not be herself with him.
Janie then runs off to be with a man named Jody. He treats her well at first, but soon, once he is the town's mayor and feels entitled and 'above his station,' he begins to demand things of her. He demands that she not sit on the store porch and talk to those 'beneath' her, and he demands that she wear her hair up in a rag - even though she has beautiful hair - because it makes him jealous to see other men look at it. So even though he appreciated her, he refused to let her be herself; she had to protect and hide herself because he felt she belonged to him. So she continued to feel oppressed.
But when Janie met Teacake, everything changed. He allowed her to be whoever she needed to be. This time, their relationship is give-and-take on BOTH sides, letting her be both a woman and an equal. So Teacake taught her the maiden language; he gave her the ability and tools and language to see herself a women (maiden), beginning all over again (maiden.)