First, here's the passage to which your question refers:
Sit down and feed, and welcome to our table.
Speak you so gently? Pardon me, I pray you;
I thought that all things had been savage here.
. . .If ever you have look'd on better days,
If ever been where bells have knoll'd to church,
If ever sat at any good man's feast,
If ever from your eyelids wiped a tear
And know what 'tis to pity and be pitied,
Let gentleness my strong enforcement be.
True it is that we have seen better days. . .
And Duke Senior goes on to acknowledge each of Orlando's question with an affirmative answer. This admission reveals the Duke's gentleness, but not "gentleness" as in mildness, but "gentleness" of birth, which denotes him a nobly born gentleman and not born to the wilds of the Forest of Arden, but to the world of the court and it's civilized ways.
Specifically, the qualities that are revealed by Orlando's questions are that the Duke has:
- "looked on better days," and not always lived an outcast "Robin Hood" sort of life;
- "been where bells knoll'd to church," which means that the Duke is a good Christian man and not a heathen;
- "sat at [a] good man's feast," which means that he has been entertained by nobility, signifying his own high social status;
- and finally, he has shed tears of empathy and pity for himself and his fellow man, signifying his sensitive and refined ability to act with generosity and understanding towards his fellow man.
This exchange, by the way, is followed almost immediately by Jaques' famous text which begins "All the world's a stage/And all the men and women merely players."
For more on this scene and Duke Senior, please follow the links below.