I'm not entirely sure specifically what 'Jalsa' is about as it could refer to various things. But generally, if it's based on a true story, it might be about real - life events, real people's experiences, or a particular historical incident. Maybe it's about a social situation, a family drama, or an event that had a significant impact on a community.
I'm not entirely sure about the specific main events as I haven't studied this movie in great detail. But generally, in a movie based on a real story, there could be events related to the central character's journey, like their rise or fall in certain aspects of life.