Names are important.
Over 700 years before Jesus was born, a prophet named Isaiah said this:
13 Then Isaiah said, “Hear now, you house of David! Is it not enough to try the patience of humans? Will you try the patience of my God also? 14 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 7:13-14
All those years later, Mary, as a virgin, became pregnant with a child. Joseph, her betrothed, was very concerned for her reputation, and certainly his own, so he decided to quietly divorce her. But after he had decided this, an Angel of the Lord visited him and said:
20b “Joseph son of David, do not be afraid to take Mary home as your wife, because what is conceived in her is from the Holy Spirit. 21 She will give birth to a son, and you are to give him the name Jesus, because he will save his people from their sins.”
– Matthew 1:20-21
Immanuel means “God with Us”.
So, 700 years before Jesus was born, God told Isaiah that He would be personally coming to earth in the form of a little baby.
Jesus is an alternative form of the name Joshua or Yehoshua which means “God Saves”.
So, shortly before the baby is born, an angel tells Joseph that his and Mary’s son is the Messiah and that He is coming to save us all.