I am having to guess a bit here.
A source of your information would be helpful.
Also brand names.
"prime 135mm" means a no-zoom lens with a focal length of 135mm.
"Extender EF 1.4x II and 2x II" most likely means an optical multiplier that goes between the lens and the camera.
Such as shown at this link:
The 2X extender will turn a 135mm lens into a 270mm lens. However, there is a penalty. You will also reduce the effective f-stop of that 135mm lens by two stops. If the 135mm lens is F5.6 it will then only function as F11. If it was F4 it would function as F8. You will need a very bright day to use the extender.
From personal experience you are likly to encounter some degree of softening of the corners of the picture. And the depth of field becomes quite narrow.
what does it means when they say that a lens (prime 135mm)is "Compatible with Extender EF 1.4x II and 2x II" and what does it do?