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
You can't spoil the porridge with butter.
Not everything that glitters is gold.
Put your trust in God, but don't make mistakes yourself
To live a life is not the same (not as easy) as to go through a field.
Crowded, but not aggrieved.
A bird is visible by its flight.
Appetite comes with eating.
The one who walks will go through.