The passage is Hosea 11:1, given here in both the ESV and the NET:
ESV When Israel was a child, I loved him, and out of Egypt I called my son.
NET When Israel was a young man, I loved him like a son, and I summoned my son out of Egypt.
And here is Matthew 2:14-15, where the Hosea passage is quoted:
ESV And he rose and took the child and his mother by night and departed to Egypt  and remained there until the death of Herod. This was to fulfill what the Lord had spoken by the prophet, "Out of Egypt I called my son."
NET Then he got up, took the child and his mother during the night, and went to Egypt.  He stayed there until Herod died. In this way what was spoken by the Lord through the prophet was fulfilled: "I called my Son out of Egypt."
Is Matthew taking the Hosea passage "out of context"? Is this a direct verbal prophecy being fulfilled? Was the Hosea passage originally referring to the Messiah? How does "fulfillment" language function in Matthew? Is there typology involved?
Those are some of the questions that come to mind.
Have at it!