Tim Dobson brings us the first of 2 christmas preaches on Immanuel. What does "God with us" mean?

Therefore the Lord himself will give you a sign: The virgin will conceive and give birth to a son, and will call him Immanuel. - Isaiah 7:14

Behold, the virgin shall conceive and bear a son, and they shall call his name Immanuel, which means, God with us. - Matthew 1:23