Complex sentence: Bill, a pragmatist, does not understand the little girl's fantasy world, and he is angered when Hitty, meaning well, erases a chalkboard, wiping out hours of Bill's hard work.
Split into simpler sentences: Bill, a pragmatist, doesn't understand the little girl's fantasy world. And he is angered when Hitty, meaning well, erases a chalkboard, wiping out hours of Bill's hard work.