in pride and prejudice What new characteristic do we learn about Jane in chapter 6 paragraph 1?

In the first paragraph of Chapter Six, we learn that Jane is in love.

It was generally evident whenever they met, that he did admire her; and to her it was equally evident that Jane was yielding to the preference which she had begun to entertain for him from the first, and was in a way to be very much in love; but she considered with pleasure that it was not likely to be discovered by the world in general, since Jane united with great strength of feeling a composure of temper and a uniform cheerfulness of manner, which would guard her from the suspicions of the impertinent.