This continues the list of men whom the Levites appointed to sing and play music as the people brought the ark to Jerusalem. (See: [[rc://en/ta/man/jit/translate-names]])
This likely means that these men served in lower positions and were assistants to Heman, Asaph, and Ethan. Alternate translation: "With them were their kinsmen who were in a lower position of power" or "The following relatives would help them" (See: [[rc://en/ta/man/jit/translate-ordinal]])
The word "gatekeepers" refers to people who guard gates or entryways. Here it refers to guarding access to the ark of the covenant and applies to Obed-Edom and Jeiel. Alternate translation: "Mikneiah, and the gatekeepers, Obed-Edom and Jeiel" (See: [[rc://en/ta/man/jit/figs-explicit]])