that day: This phrase is important in the prophets. It refers to the coming day of the Lord (see Joel 1:15; 2:1; Amos 5:18), when the Lord will act decisively in human history for his people.
you will call Me ‘my Husband,’ and no longer call Me ‘my Master: On this day, Israel will have a new relationship with God. Israel will no longer call God “master” (Hebrew ba‘al), which suggests subservience and was also the name of the main Canaanite fertility god. Instead, she will call the Lord “husband,” implying partnership and companionship (Genesis 2:23–24).