en_tn/mat/01/23.md

Behold ... Immanuel

Here Matthew quotes the prophet Isaiah.

Behold, the virgin

"Pay attention, because what I am about to say is both true and important: the virgin"

Immanuel

This is a male name. (See: rc://en/ta/man/translate/translate-names)

which means, "God with us."

This is not in the book of Isaiah. Matthew is explaining the meaning of the name "Immanuel." You could translate it as a separate sentence. AT: "This name means 'God with us.'"