The word Zaphon is used four times in the Hebrew Bible. The word literally means “north.”
Twice the word is used to refer to a city in Gad on the east bank of the Jordan River (Joshua 14:27 and Judges 12:1). In these two passages, we are not told anything specific about the city. Zaphon is simply used as a landmark.
The King James Version also uses the word Zaphon in Psalm 48:2 and Isaiah 14:13, whereas most modern versions translate the word as “north.”
Compare these two translations, with emphasis added:
KJV Psalm 48:2: “Beautiful in its loftiness, the joy of the whole earth, like the heights of Zaphon is Mount Zion, the city of the Great King.”
ESV Psalm 48:2: “Beautiful in elevation, is the joy of all the earth, Mount Zion, in the far north, the city of the great King.”
Mt. Zion (Jerusalem) is near the middle of Israel, but when the kingdom split, Jerusalem was then near the northern border of Judah (the southern kingdom). While this is a possible explanation for Zaphon being equated with Jerusalem in the ESV, it also seems that the term Zaphon was used in Canaanite literature to refer to a “cosmic mountain par excellence in Northwest Semitic regions” (Niehr, H., “Baal-Zaphon,” Dictionary of Deities and Demons in the Bible Online, van der Toorn, Becking, and van der Horst, ed., http://dx.doi.org/10.1163/2589-7802_DDDO_DDDO_Baal_Zaphon, accessed 1/19/22). It may be that the biblical author in Psalm 48:2 is making a conscious comparison between one of the Canaanite sacred places (Baal-Zaphon) and the most sacred place in Israel. In other words, it is not Baal-Zaphon where God can be encountered, but Mt. Zion.
In Isaiah 14:13 the king of Babylon says, “I will sit enthroned on the mount of assembly, on the utmost heights of Mount Zaphon.” This seems to use the term Zaphon in the same way that Psalm 48:2 does; however, the interpretation is complicated by the context. Some see this passage as referring to Satan and his sin of pride that brought on the fall, while others believe this refers only to the Babylonian king and his sin of pride (no doubt inspired by Satan). In either case, the point is that the individual speaking attempted to exalt himself above the most sacred site(s).
In conclusion, Zaphon is a city in Israel of no particular significance, but the name of the city takes on a sacred significance for Canaanites, and that may color the way the term is used in biblical literature.