What does the sentence heart as big as all outdoors mean?

The phrase "heart as big as all outdoors" is a metaphor that describes someone with an immense capacity for love, kindness, and generosity. It suggests that the person's emotional warmth and compassion are boundless, much like the vastness of the outdoors. This expression conveys the idea that the individual is open-hearted and caring, willing to embrace others and offer support without limits.