would make (someone) happy, would please
Nos alegraría mucho que pudiera venir con nosotros.
We would be delighted if you could come with us.
Si necesitas mi consejo, me alegraría dártelo.
If you need my advice, I’d be happy to give it to you.
Pos me alegraría, porque a mí ni caso me hace.
Well, I'd be happy, because he doesn't pay me any attention.
— Los olvidados (1950)
Me alegraría mucho si pudieras venir.
I’d be very happy if you could come.
Pensé que te alegraría ver a Tom.
I thought you’d be happy to see Tom.