“Jesus.” The angel would have almost certainly spoken to Mary in Aramaic, and thus would have said the Aramaic name of Jesus, “Yehoshua,” which means “Yahweh is salvation.” Thus the angel explains by saying, “for, he will save his people from their sins.” “Yehoshua” is the name “Joshua” in the Old Testament, and Joshua was one of the types of Christ in the Old Testament and there are some profound parallels between Joshua and Jesus.
“it is he.” This is emphatic in the Greek; “he” is put as the very last word in the sentence for emphasis. That would only be confusing in English, so we would have to use capital letters or bold letters. We might say, “Because HE will save his people from their sins.” We place a little more emphasis on it by saying, “it is he,” (cp. NASB).
“sins.” [For more on sin, what it is and what it does, see commentary on 1 John 1:7, “sin”].