Help I-130

Hey everyone I need some info. I applied for a I-130 for my hubby's daughter in Cuba. Immigrstion shows they sent me a letter but the post office returned it. They said it was approved. So now what am I waiting for and now long does it take. I was born here in the USA in Miami so I know I don't need for a vis to become avalible. So what happens now. Can you please inform me.