¿Entiendes la palabra: "motorway"?
I am not sure why this word is confusing for Spanish speakers but for some reason it is. I have noticed this through experience that when I use this word I get blank faces staring back at me!
The translation is "autopista" and when you go to the UK will notice that all the main roads use an "M": M1 (to the north), M25 (ring road around London), M20 (towards Dover) and the M3 (towards my hometown which is Bournemouth).
The Americans use different terminology and you are more likely to here words such as "freeway" or "highway".
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 10 años de experiencia enseñando inglés a españoles.