There is no one answer to this question since bullet journals can be used for a variety of purposes, including but not limited to tracking habits, organizing to-do lists, and taking notes. However, some ideas of what could be included in a bullet journal are as follows:
-A key or legend to help you keep track of the symbols you use to denote different types of information
-Monthly, weekly, and/or daily spreads to help you plan and track your activities
-A Future Log to help you stay on top of upcoming events and deadlines
-A Habit Tracker to help you keep track of any goals or resolutions you may have
-A To-Do List to help you stay organized and on top of your responsibilities
-A Note-Taking section to help you jot down ideas, brainstorm, or record important information
The beauty of bullet journaling is that you can tailor it to fit your specific needs, so feel free to get creative and add in anything that you think would be helpful for you!