What does Ruth 2:3 mean?

Ruth and Naomi are in Bethlehem. Without a source of income, Ruth has decided to glean barley after the harvesters (Ruth 2:2). Early in the morning, she happens upon a field owned by Boaz, a relative of her late father-in-law. The field is a section of open land not separated from other owners by a fence.

This is a summary statement; it doesn't describe Ruth's actions to this point. There's no indication she visited other fields before she came to Boaz's. She came to Boaz's field without knowing who he was or that he was related to her father-in-law (Ruth 2:19–20). Nor did Naomi send her; Naomi is so deeply depressed, shaken by the trauma of losing her husband and sons, that she doesn't even seem to remember that her husband has a kinsman-redeemer who could help. God sends Ruth to Boaz's field.

Once she arrives, she asks permission of the harvest foreman to glean (Ruth 2:2, 7). She's smart to do so; women aren't safe in fields (Judges 21:17–24).

When Boaz comes to the field, he asks his servant about her and is impressed by her devotion to an Israelite widow. Ruth has revoked her heritage and her gods and declared her allegiance to Naomi's people and the God of Israel (Ruth 1:16–17). Boaz not only invites her to continue gleaning in his field, but he also protects her and makes sure she can gather enough for the women to live on (Ruth 2:4–23).