The postures in hot yoga and specifically Bikram yoga will flush through you. Thoughts and emotions will pop up and become very clear. Your intuition will become stronger and you will realize how the things in your life really affect you. If you dislike your job, or if there's someone you can't stand. If you have a lot of unexpressed emotions or if there is something you need to change, you will become very aware of it. But only if you are open to that.
You also sweat loads for 90 minutes straight which also clears out a lot of toxins that affect you negatively. Sweating detoxifies you, and since everything in your body is connected to your mind and vice versa, sweating has incredible effects on how you feel. Try and journal how you normally feel before you start your yoga journey and see after having practiced regularly for 3 weeks and compare. I promise that you'll feel better, and you won't want to stop. This is a lifelong journey.