This has been a recurring theme in many meditations.
To me, it represents the death of Ego by fire turning to ash and a subsequent rebirth to a higher vibration, full of colour and energy.
For the Phoenix to appear, I am to prepare for this to occur. The Phoenix knows this process is about to happen, burning the old patterns and programs to ash. It flies home to the place of birth and rebirth, a sacred place, home, high on the ancient spire where a nest is ready. It is a time of rest and recuperation, a time to face mortality. But it is also a time to rejuvenate, to repair, to shuffle off all that has weighed one down and become light again, with new wings and feathers and fly again into new experiences.