A sound bath is an immersive meditation experience where you are literally bathed in sound.
Sound travels and emits vibrational frequencies. Each instrument has it's own unique frequency that comes in contact with your energetic field. When sound vibrations come in to contact with your energetic vibration it can help to clear blocked or stuck energy within the energetic centers of the body (chakras).
Crystal singing bowls are unique to the sound bath experience because they are specifically tuned to the 7 energy centers of the body (chakras).
The word "chakra" in Sanskrit literally means "wheel". According to Yoga philosophy, they store the energy around our thoughts, emotions, actions, memories and experiences. There are a variety of ways to clear these energy centers (like reiki, acupuncture, etc). However, attending a sound bath is a simple yet supportive practice you can do regularly in order cleanse stuck or stagnant energy to promote healing.
You don't need to understand how it works in order for it to be effective. There is no wrong way to participate in a sound bath. Most people lie down on their backs while the practitioner (sound healer) guides you in to a state of deep relaxation. From there, the healer will play a variety of instruments in an around your energetic space.
This is a great practice if you have difficulty relaxing, or meditating on the breath. There are an infinite number of doorways into meditation. Find one that suits you.