These are the names of men. See how you translated Joab and Zeruiah (Joab's mother) in [2 Samuel 2:13](../02/13.md). (See: [[rc://en/ta/man/jit/translate-names]])
This word means that the person is descended from Ishmael. Some versions say "Israelite" here. See the footnote. You may want to choose the word that is used in the majority language Bible in your area.
This is a polite way of saying that he had sexual relations with her. Alternate translation: "who had sexual relations with Abigail" or "who lay with Abigail" (See: [[rc://en/ta/man/jit/figs-euphemism]])