This is the 11413th most frequent Russian word.
длится
"Длится" means "lasts" or "continues."
Here, 'длится' is used to describe the duration of time for which an event, the movie, is taking place.
Фильм длится два часа.
The movie lasts for two hours.
In this context, 'длится' specifies the duration of the lesson.
Урок длится сорок пять минут.
The lesson lasts for forty-five minutes.
Here, 'длится' indicates the continuous and ongoing nature of the trial over a period of time.