Light is an electromagnetic wave
Changing electric fields generates magnetic fields
Changing magnetic fields generates electric fields
Can set up a cycle where one field causes the other:
The E and B fields oscillate in strength, and the disturbance moves forward.
To describe the wave you need to specify
Direction it is moving
Strength of the fields (its intensity)
Frequency or Wavelength of the oscillation ( and are inversely related)
Orientation of the electric E field:  up or sideways (polarization)
You do not need to specify its speed
In a vacuum all lightwaves move at the same speed c = 3108 m/s