‘ And Naomi said to Ruth her daughter-in-law, “It is good, my daughter, that you go out with his maidens, and that they do not meet you in any other field.”
Naomi the expressed her approval of what Boaz had said. As she had remained at home, a fact which suggested that she was old and infirm enough not to have joined the gleaners, she had probably had time to worry about Ruth's welfare. Who knew what unscrupulous field owners, or feisty young reapers, or jealous gleaners, or unpleasant young women who looked down on an alien, might do to take advantage of a virtually unprotected, and seemingly beautiful, young woman? But now she knew that YHWH had been watching over Ruth, and was content. So she confirmed Boaz's words and called on Ruth make sure that she went out into the fields with Boaz's young women, and not work in any other field where unpleasant people could meet her (or more literally ‘fall upon her', i.e mistreat her or misuse her).