What does Ruth 3:5 mean?

Ruth has worked in Boaz's fields for two months. The harvest is over, and she will have little chance to spend time with him in town as he is a wealthy landowner of some renown, and she is a Moabite widow. Ruth's mother-in-law, Naomi, thinks Boaz would make Ruth a good husband. But their social standings and Ruth's complete lack of a dowry make it impossible for Naomi to arrange the marriage through normal channels.

Instead, Naomi tells Ruth to take off her widow's clothes and dress like a woman looking to marry. After Boaz has celebrated a successful harvest and fallen asleep, surrounded by sleeping witnesses for both privacy and propriety, Ruth is to approach him carefully. Finally, Naomi instructs Ruth to wake up Boaz by uncovering his feet to the cool night air. (Ruth 3:1–4). Ruth agrees.

Naomi doesn't seem to realize that Ruth has her own agenda. Naomi had casually mentioned that Boaz is a kinsman-redeemer of her late husband's (Ruth 2:20). That means Boaz may be responsible for buying Elimelech's land which would provide for Naomi's needs. Ruth intends to challenge Boaz to fulfill that responsibility (Ruth 3:9). But she wants more. She wants a levirate marriage. By the law, a widow could marry her late husband's brother to bear a son in her husband's name (Deuteronomy 25:5–6). Boaz isn't required to do this; he's not Elimelech's brother, and Ruth isn't even blood-related to Elimelech.

But Boaz agrees (Ruth 3:13). Within a year, Naomi will get her wish of seeing Ruth successfully married. But she'll also hold a baby boy in her lap, removing the shame of her inability to provide her husband with an heir (Ruth 4:13–17).