To add alternative text (Alt. Text) to Images, Shapes, and Graphs in Excel,
Right-click on the Image, Shape, or Graph

Select "Alt. Text” to edit your alternative text.

Describe the image in the "Description" box.

In this example, you could say, “The SNHU logo.” If the image shape or icon is only "decorative," then put a check mark in the box "Mark as decorative" to let the screen reader and user know that image is not important content.
For more detailed instructions, go to the articles:
To run the Accessibility Checker in Excel,
Select “Review”

Select “Check Accessibility”

For detailed instructions, go to the article: How to Use Accessibility Checker in Excel (Microsoft 365 Web App)
Give Meaningful or Descriptive Content to Links
For detailed instructions, go to the article: How to Create Meaningful Links in Excel (Microsoft 365 Web App)
Additional Resources
For detailed instructions, go to the article: