A radian is a unit to measure angles.
One turn of a circle has 2π radians in measure.
It's equivalent to a measure of 360 degrees.
π radians are equivalent to 180 degrees, so if we need to convert from radians to degrees, we just multiply by 180 and divide by π.
For example, to convert 2π/3 radians to degrees:
2π/3 radians is equivalent to 120 degrees.