S. 573 proposes to officially name a mountain in Alaska as "Denali." The bill specifies the exact location of the mountain by its geographical coordinates. It also states that any existing references to the mountain in U.S. laws or documents should be updated to the name "Denali."
Simple Explanation
In Alaska, there is a mountain, and this bill wants to officially give it the name "Denali." This means that anytime the mountain is mentioned in anything from the U.S., they'll use its new name, Denali.