High rise refers to pants that sit higher on the waist than normal. High rise (or high waisted) pants tend to have a slimming effect, and will make you look taller because they make the legs seem longer.
High-rise pants are typically more common among women, who clearly enjoy the slimness of high rise pants, but can be appropriate for men as well, especially for those who are going for a more hipster or European look.
High rise pants can be difficult to pull off, and done poorly can come across as like the geeky guy in suspenders, but done properly, pants with a higher rise can be used to create a unique look that can’t be achieved with mid-rise or low-rise pants.
Also, because high rise pants will tend to make you look taller, wearing pants with a slightly higher rise can be a good thing for shorter guys. The higher waistband can also help tuck in your gut if you’ve put on a few extra pounds, but just make sure your stomach doesn’t spill over the top of the pants.