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
Don't bring your set of rules in a foreign monastery
Your own shirt is closer to your body.
You can't help grief with tears.
If you are chasing two hares at once, you won’t catch a single one.
You can't hide an awl in a bag.
You see your friends in the times of trouble.
Each sandpiper praises its swamp.
The best is the enemy of the good.