The boy is 6 now, and physically he seems like a normal, healthy kid. However, he was born several weeks prematurely, and has some developmental delays as a result. He has been having speech therapy for a few years now, but his speaking is still indistinct, and now it's affecting him academically.
If you can't speak properly, it's very difficult to learn how to read. When you first learn to read, you sound out the words and your brain "hears" them by putting together the sounds you are making. Even though the boy knows all the letters and the sounds each one makes, he can't read because his brain doesn't recognize the words when he puts the sounds together. He's not hearing anything close to what he actually says.
The good news is that this should be completely curable, although it will take some effort, and a good deal of money, too. So his mom is dealing with the insurance company to see if they'll pay for the additional therapies he needs to really bring him up to an age-appropriate level. It really needs to be done now, before he falls too far behind in school.
Plus, his mom said, ... it would be so great if [his father] could understand him.