Cherub: a place in Babylonia that some of the returning exiles came from, written in Hebrew exactly like the word for a cherub
Two verses in the Bible use this word, and they are really the same verse twice: a written list of the families who came back from Babylon, copied into both Ezra and Nehemiah. Most of that list names people by their ancestor or by their hometown in Judah. Then comes a short group listed instead by the Babylonian places they came up from: Tel-melah, Tel-harsha, Cherub, Addan, Immer. What the text says about them is the point of naming them at all. They could not produce their family records, so they could not show that they were Israelites.
Cherub in these two verses is one of those Babylonian places, not a heavenly being. The name is written exactly like the Hebrew word for the winged beings that guard God's holy ground and stand over the ark (כְּרוּב), and on the page the two are impossible to tell apart. Whether the town's name had anything to do with those beings, nobody knows. Apart from the winged beings themselves, this spelling turns up in the Hebrew Bible only here.
The place has never been found. Scholars who work on where the deported Judeans actually lived put settlements like these out in the Babylonian countryside, where whole villages of exiles were resettled, but no known site can be matched to the name with confidence. Nehemiah's copy of the list even spells the next name a little differently, "Addon" for Ezra's "Addan", a small sign of how these unfamiliar names drifted as the list was copied.
What the list cares about is not geography but standing. The families from these places sit in the same paragraph as priests who could not find their names in the records and were kept from the priests' food until a ruling could be made. Coming home was one thing. Proving you belonged was another.