With accent marks:
Сы́тый голо́дного не разуме́ет.
A well-fed man does not understand a starving one.
A well-fed, prosperous person does not want (and often is not able) to understand what it is like to be hungry.
The old Russian word "разуметь" in this case means "understand".
Other Russian proverbs
Patience and labor will grind everything.
Without labor, you can not even catch a fish in the pond.
We don't appreciate what we have but we cry when we lose it.
They do not seek good from good.
Forewarned is forearmed.
You can't command to the heart.
Fear has big eyes.
A titmouse in hands is better than a crane in the sky.