This chapter, as throughout the novel, is full of imagery and figurative language. One exemplary moment is Jane's realization of the shattered chestnut tree:
“It stood up, black and riven: the trunk, split down the center, gasped ghastly. The cloven halves were not broken from each other, for the firm base and strong roots kept them unsundered below; though community of vitality was destroyed—the sap could flow no more: their great boughs on each side were dead, and next winter’s tempests would be sure to fell one or both to earth; as yet, however they might be said to form one tree—a ruin, but an entire ruin.”
This description is rich with visual imagery, & Bronte's attention to detail is striking. She's also using metaphor and symbolism here, with the tree representing Rochester and Jane's relationship. They are connected as one through their love, yet cleaved in half by the secret Jane does not yet know. This is an example of the pathetic fallacy, in which the natural world reflects the personalities and emotions of the characters.
This chapter is also marked by language blurring the line between fantasy and reality. Jane's dreams figure prominently in her decisions, and inform her perceptions of her waking world as well. Thus her narrative takes on a dream-like quality through Bronte's language.
I believe she is taking German lessons but is later asked to give them up and learn Hindustani, the language St. John is studying in preparation for his missionary work.