Narrow means less wide or to make less wide. When you narrow down your choices, you decrease the number of choices. A road might be too narrow for a car.
When used to describe something physical such as a street or hips, narrow simply means not wide. Similarly, with quantities it means not much like when you win your basketball game by a narrow margin. But if you use it to describe an attitude, it has the negative meaning of not wide or open enough. If you're narrow-minded, you don't see the big picture –– sometimes it means you think in narrow stereotypes.