If you are dreaming about lying then you may have some insecurities about someone in your life. You may also be dealing with some guilt if you have recently lied to someone. In many cases dreaming about lying is a representation of your own perceptions about truths, realities, and how you navigate honesty in your waking life.
It is also possible that you may be concerned with how people in your life perceive you, or if they consider you an honest person or not. In all cases in life, whether that is dreaming or wake, the truth will always set you free.