Jauhar was a practice done a long, long time ago in India. It happened when a group of people, usually women, would choose to end their life instead of being captured or taken over by their enemies.
Think of it like this: You have a really important toy that you love playing with, and you don't want anyone else to take it away from you. So instead of letting them take it, you break it so no one can have it.
The people who did jauhar believed that it was better to die than to be captured by their enemies because they would be treated very badly. So they would get together, say goodbye to their loved ones, and then set themselves on fire so that they would all pass away together.
It's a very sad practice and thankfully, it doesn't happen anymore. We don't believe that it's okay to take our own lives. We should always try to live as long and happy of a life as we can.