Isaiah 19:16 In that day the Egyptians will become weaklings. They will shudder with fear at the uplifted hand that the Lord Almighty raises against them. 17 And the land of Judah will bring terror to the Egyptians; everyone to whom Judah is mentioned will be terrified, because of what the Lord Almighty is planning against them. 18 In that day five cities in Egypt will speak the language of Canaan and swear allegiance to the Lord Almighty. One of them will be called the City of the Sun.
Isaiah 19:18 New International Version
In that day five cities in Egypt will speak the language of Canaan and swear allegiance to the LORD Almighty. One of them will be called the City of the Sun.
New American Standard Bible
On that day five cities in the land of Egypt will be speaking the language of Canaan and swearing allegiance to the LORD of armies; one will be called the City of Destruction.
It is a play on word:
עיר החרס Ir-ha-kheres city of the sun עיר החרם Ir-ha-cheres city of destruction
Isaiah prophesied that the City of the Sun in Egypt would be destroyed and converted.
Matthew Poole explains:
The city of the sun; or, as the Grecians call it, Heliopolis; which the Egyptians called On, Genesis 41:45; which was a very eminent city, and a chief seat of idolatry, being a city of priests, as Strabo reports; and therefore its conversion to the faith was more wonderful.
Note the comments of Ellicott on Isa 19:18 -
The city of destruction.—There is probably something like a play on the name of the Egyptian city On, the Greek Heliopolis, the City of the Sun (Heb., Ir-ha-kheres), and the word which the prophet actually uses (Ir-ha-cheres), the “city of destruction.” The paronomasia, like in character to Ezekiel’s transformation of On into Aven, “nothingness,” or “vanity” (Ezekiel 30:17), or Hosea’s of Beth-el (“house of God”) into Bethaven (“ house of nothingness”) (Hosea 4:15), was intended to indicate the future demolition of the sun-idols, and is so interpreted in the Targum on this passage, “Bethshemesh (i.e., Heliopolis), whose future fate shall be destruction.” The word for destruction is cognate with the verb used of Gideon’s breaking down the image of Baal, in Judges 6:25; and in Jeremiah’s prophecy (Jeremiah 43:13), “He shall break the pillars in the house of the sun,” we may probably trace an allusive reference to Isaiah’s language. Other meanings, such as “city of rescue,” “city of protection,” “city of restoration,” have been suggested, but on inadequate grounds. The Vulg. gives civitas solis. The LXX. rendering, “city asedek,” apparently following a different reading of the Hebrew, and giving the meaning, “city of righteousness,” was probably connected historically with the erection of a Jewish temple at Leon-topolis by Onias IV., in the time of Ptolemy Philomêtor, which for some two centuries shared with the Temple at Jerusalem the homage of Egyptian Jews. Onias and his followers pointed to Isaiah’s words as giving a sanction to what their brethren in Palestine looked on as a rival and sacrilegious worship.