What’s the difference between “beau” and “belle”?

[sweet gale]

In the grammar book I’m reading it translates both “beau” and “belle” as “pretty,” and says that belle is used before a vowel sound or mute h. But the example sentence was “C’est une belle maison” which is neither a vowel nor a mute h.

[jaunty vortex]

beau -> masculine
bel -> masculine before vowel or mute h
belle -> feminine

maison is feminine, so you use belle here

arbre is masculine and starts with a vowel, so you'd use bel