7 It will be a unique day—a day known only to the LORD—with no distinction between day and night. When evening comes, there will be light.

Read Zechariah 14:7 Using Other Translations

But it shall be one day which shall be known to the LORD, not day, nor night: but it shall come to pass, that at evening time it shall be light.
And there shall be a unique day, which is known to the LORD, neither day nor night, but at evening time there shall be light.
yet there will be continuous day! Only the LORD knows how this could happen. There will be no normal day and night, for at evening time it will still be light.