Final answer:
Jane Eyre leaves Lowood for Thornfield Hall in the summer month of June, after spending a decade at the institution, seeking new experiences and growth.
Step-by-step explanation:
Jane Eyre leaves Lowood in the month of June, after having spent eight years there as a student and two years as a teacher. The novel Jane Eyre by Charlotte Brontë doesn't specify Jane departure in the exact terms of 'which month'; however, the narrative implies it is in summer, after she sees an advertisement for a governess position in Thornfield. Motivated by a desire for new experiences and personal growth, Jane advertises her services as a governess, and upon receiving a response, she departs for Thornfield Hall, marking a new chapter in her life.