Someone who's blind can't see. People who are blind can often get around easily with the aid of a cane and sometimes a service dog.
You might get hit by a baseball and end up blind in one eye, or be temporarily blind after a trip to the eye doctor. The word also means "without looking," as in a blind taste test of three different brands of chocolate milk. A figurative way to be blind is to refuse or be unable to see the truth: "He was blind to the reality of the situation." This tendency can be called a person's "blind side."