Brackets. This verse is omitted in many of the early and diverse manuscripts, including some manuscripts from the Majority Text, so it is omitted in some of the modern versions, such as CJB, ESV, RSV, and NJB. We put it in brackets to mark the fact that it is doubtful.
“Look!” The Greek word is idou (#2400 ἰδού), and it is used to get our attention. See commentary on Matthew 1:20.
“your mother.” There is no mention of Joseph; he had apparently died. See commentary on John 19:27.