At this stage, your nephew is making pre-speech vocalizations, often called cooing or pre-babbling. He isn't saying specific words just yet, but he is definitely communicating!
Based on the sounds he's making in the video, here is what he is "saying" in baby language:
"I'm listening and responding to you!" When you speak to him, he immediately makes those high-pitched squeaks and soft sounds right after. He is practicing the back-and-forth flow of a real conversation.
"Look at what my voice can do!" He is experimenting with his vocal cords, changing his pitch, and figuring out how to make different sounds.
"I'm engaged and trying to copy you." You can see his little mouth moving and his eyes looking right toward you as he coos—he's actively trying to mimic the sounds of human speech.
It's his way of having a full conversation with his Mama!
