What does Luke 1:40 mean?

Zechariah and Elizabeth are an aging priest and his wife, who struggled with an inability to have children (Luke 1:5–7). In an angelic encounter, Zechariah learned that they would finally have a child (Luke 1:13), and the boy would become a powerful herald of the Messiah (Luke 1:13–17). For several months, Elizabeth has been in joyful seclusion (Luke 1:24–25).

Her relative, Mary, has also been given amazing news (Luke 1:26–33). Though a virgin, she is bearing the very Son of God. Mary's Child is the Messiah whom Elizabeth's son, known as John the Baptist, will proclaim (Luke 3:2–3). At the time Mary comes to visit, Elizabeth is six months pregnant (Luke 1:36). When Mary arrives, the unborn child in Elizabeth's womb will react to the presence of the also-unborn Messiah (Luke 1:41–42). This begins a rejoicing encounter between the two women (Luke 1:43–56).