What is pg.173 about?

On pg. 173 (my copy), Billy is leaving to go hunting..... the last thing Billy heard before he left was his mother telling him to be careful.

The last thing I heard as I left the house was the voice of my mother. “Be careful, Billy,” she said, “and don’t stay out late.” It was a beautiful night, still and frosty. A big grinning Ozark moon had the countryside bathed in a soft yellow glow. The starlit heaven reminded me of a large blue umbrella, outspread and with the handle broken off.