This is what a transverse wave looks like, note that it is made by the medium vibrating perpendicular to the direction the wave is moving. What does that mean? As you see the wave defects up and down but the wave is actually traveling to the right.
The up and down arrow represents the amplitude.
The left and right arrow represents the wavelength.
Another thing to note is the equation for a wave. v = λf
v represents the velocity of the wave, it is how fast the wave is traveling through the medium. Its units are a distance over time (m/s)
λ (lambda) This represents the wavelength, its units are a distance (km, m, mm, nm, ...)
Transverse waves are associated with light.