Microsoft is improving Copilot integration in the Edge browser with AI-powered smart keywords. This will allow the AI to generate important keywords from the PDF and then help you analyze each topic. 
Copilot in Edge already lets you summarize all types of documents, including PDFs.
You can open any PDF in the Edge and interact with the AI to ask questions, summarize, and review the content. For example, you can ask Copilot to summarize an entire PDF or answer specific questions about the document.

Edge’s PDF reader is now expected to gain a new feature that generates keywords. These keywords, which are one or two-word phrases, highlight important content within a document and make it easier to locate relevant information.

As spotted by browser researcher Leo, Microsoft has already made some changes related to this feature in Edge Canary, including updating the icon and tooltip for the keyword generator.
The tooltip now indicates that these keywords will be generated with the help of Copilot.
Edge’s PDF reader will not only highlight these “smart keywords” within the document but also allow users to click on them to get additional information through Copilot.
It’s unclear when the feature will be released for everyone, but if you’re lucky enough, you might already have access to smart keywords feature in Edge Canary or Dev.