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
One in the field is not a warrior.
Your own shirt is closer to your body.
In a healthy body, healthy mind.
If you are chasing two hares at once, you won’t catch a single one.
The apple never falls far from the tree.
Don't go to the woods if afraid of wolves.
Each sandpiper praises its swamp.
What goes around comes around.