A brook is a very small, running stream of fresh water. Brooks often come from a spring.
A broom is a brush on the end of a long stick that is used for sweeping loose dirt off a floor. Brooms do not work very well on carpeted floors so most people use vacuum cleaners instead.
Many animals are brown, and dirt is brown. The colour brown can be made by mixing a few other colours of paint together without thinking, you'll usually get brown this way! The horse in the picture is brown.