Practice circles are meetings where those that communicate with spirit get together and "practice" their abilities. Psychic senses are like a muscle, the more you work that muscle the stronger it gets.  It is a safe place for us to try something new and stretch our clairs (psychic senses) a bit more so we can give better readings to our clients. It's experience really and the more experiences we have the greater our capacity to bring through those healing messages and spirit guidance our clients are needing and wanting.