You can easily track and estimate time on your cards. When time tracking is enabled in the board settings, you will get a “time tracking” -button inside your card.
Use the timer, add manual entries and set estimates
When you open the time tracking window, you can either use the timer or add manual time entries. You can also add an estimate for how much time you’re going to spend on that card. All the time that has been logged on a card will be shown as a list, with date, description, who logged it, and time spent.
View hours spent vs estimated without opening the card
When you have set an estimate or added time entries, “hours spent vs estimated” will show up on your card.
You can generate and export timesheets on both board- and team level. Read more here.