This is a euphemism that refers to having sexual intercourse. AT: "He had sexual relations with her" (See: [[rc://en/ta/man/translate/figs-euphemism]])
This phrase probably refers to how Naomi will again experience joy and hope in her life as a result of having a new grandson. AT: "one who brings joy to you again" or "one who will make you feel young again"
"Seven" was the Hebrew number of completeness. Naomi's sons both died before they produced any offspring, but Ruth bore a grandson to Naomi by Boaz. AT: "better to you than any son" (See: [[rc://en/ta/man/translate/figs-idiom]])