Pa Bailey is a living incarnation of the old-timey "Father knows best" maxim.
As George Bailey's dad, he's an honest man who founded the Bailey Brothers Building and Loan with Uncle Billy in order to help the people of Bedford Falls buy their own affordable houses. This ends up acting as a bulwark against the greedy designs of Mr. Potter, who wants to control all of the businesses in town.
POTTER: Have you put any real pressure on those people of yours to pay those mortgages?
PA BAILEY: Times are bad, Mr. Potter. A lot of these people are out of work.
POTTER: Then, foreclose!
PA BAILEY: I can't do that. These families have children. [...]
POTTER: They're not my children.
PA BAILEY: But they're somebody's children.
Pa is a compassionate guy. He knows what's up with Potter:
PA BAILEY: Oh, he's a sick man. Frustrated and sick. Sick in his mind, sick in his soul, if he has one. Hates everybody that has anything that he can't have. Hates us mostly, I guess.
Although Pa Bailey wants George to go to college and travel the world, he'd like him to run the business after he graduates. George doesn't recognize how important the Building and Loan is to the town. He accidentally lets this slip, saying, "I couldn't face being cooped up for the rest of my life in a shabby little office … I want to do something big and something important."
Pa Bailey responds by saying:
PA BAILEY: You know, George, I feel that in a small way, we are doing something important. Satisfying a fundamental urge. It's deep in the race for a man to want his own roof and walls and fireplace, and we're helping him get those things in our shabby little office.
Shortly after this Capra-esque conversation, Pa has a stroke and dies. It will take George Bailey the rest of the movie to grow into his father's shoes, but the old man taught him well.