During a root canal treatment, the inflamed or infected pulp is removed, and the inside of the tooth is carefully cleaned and disinfected, and then filled and sealed with a rubber-like material called gutta-percha. Afterwards, the tooth is filled for protection and then crowned. After restoration, the tooth will continue to function normally.
Contrary to jokes about the matter, modern treatment is very similar to having a routine filling and usually can be completed in one or two appointments; depending on the condition of your tooth and your personal circumstances. You can expect a comfortable experience during and after your appointment.