The phrase "shed pounds" is a slightly more interesting way to explain losing weight.
To "shed" something means to lose it little by little. For example, pets shed their hair around your house. And snakes shed their old skin as they grow larger. Also, you "shed" things that you want to get rid of or that you don't need any more.
"Pounds" are the unit of measurement that we use in America to weigh people. One kilogram equals about 2.2 pounds. When you say you want to "shed some pounds", it means that you want to lose weight and become lighter. People often use "pounds" to talk about their weight, even when they're not measuring themselves or talking about how much they weigh. For example:
I've been packing on the pounds lately.
This means that you've been getting fatter.
Doesn't it look like he's put on a few pounds?
This means "Don't you think he looks fatter than he used to be?"