When you become Frightened, you enter one of three states: Fight, Flight, or Freeze. The effect that caused the condition determines the state, or the GM chooses one if it doesn’t specify.
Fight: You must move toward the source of your fear and, if possible, use your Actions to attack or otherwise confront it. You cannot willingly move farther away from the source.
Flight: You must move away from the source of your fear by the safest available route. If possible, you must use your Actions to Dash or otherwise increase the distance between you and the source. You cannot willingly move closer to it.
Freeze: You are Winded and cannot willingly move closer to the source of your fear. You can still take Actions normally.
Duration: Frightened lasts for the duration specified by the effect that caused it. At the end of each of your turns, you can make a Charisma Saving Throw to end the condition, unless the effect specifies otherwise.