A: The term “fell on his neck” is used 5 times in the Bible: (Gen 33:4)(Gen 45:14)(Gen 46:29)(Lk 15:20)(Acts 20:37).
While similar to a “hug” in its uses, it appears to be more emotional. In all but (Lk 15:20 – a parable), “weeping” is connected with it. In (Gen 33:4)(Lk 15:20)(Acts 20:37), a “kiss” is also given.
In (Acts 20:37), the “Ephesian elders” fell on Paul’s neck, wept, and kissed him because he had told them in (Acts 20:25) that it would be the last time they would ever see him (he appears to have been mistaken: see 1 Tim 1:3).