According to Moz, Page Authority is a score that predicts how well a specific page will rank on search engine result pages (SERP). Page Authority scores range from one to 100, with higher scores corresponding to a greater ability to rank. Page Authority is also referred to as PA for short. Using primarily link data we want to estimate how well your page can rank.
The higher your Page Authority score is, the better chance your page has of ranking high on Google’s search engine results pages.
Monitoring the page authority of each one of your web pages can be beneficial in determining whether certain inbound marketing strategies are working or not. For instance, if one of your web pages has a low page authority, then you know that there’s something about it that may be hurting its ranking. Comparing it to other pages and reviewing the link profile will help you to figure out what needs to be changed and what you may want to review or avoid doing in the future.
You can also learn more about page authority and how it relates to domain authority here.