What does Judges 19:15 mean?

The sun has already set as the Levite, with his servant and concubine and two donkeys, arrives in Gibeah to spend the night. They are on their way from Bethlehem to Ephraim and plan to be gone in the morning (Judges 19:9–14). The Levite decided not to stop for the night in Jebus, which at that time was controlled by non-Israelis (Judges 1:21). Either he felt hospitality would not be offered, or that they would be in real danger. It's also possible the Levite simply objected to staying with Gentiles.

Instead, he continued a few more hours, after dark, to a town populated by fellow Israelites. As it happens, nobody in Gibeah offered these strangers any hospitality, at all, even though they are also Israelites. This is a subtle, chilling warning that Gibeah is not as safe a place as the Levite had assumed it to be.

The Levite and his party give up and sit down in the city square, which would have been located just inside the gates of the city. Spending the night in the city square would have been both uncomfortable and unsafe. Travelers would be exposed to the weather, as well as to those with criminal motives. It would be less dangerous than camping in open terrain, however.