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
Better to see once than hear a hundred times.
Strike the iron while it's hot.
Live for a century, learn for a century, but die being a fool anyway.
Fear has big eyes.
A wolf is fed by his legs
Repetition is the mother of learning.
Where there is no fish even a crayfish is a fish.
When I eat I am deaf and mute.