Use tables mainly to display data that fits well into rows and columns.
Add table headers to describe the contents of the table columns. (Table Properties>Headers.)
Add table caption and summary to provide more information about the table for screen reader to pick it up.
Avoid spanned rows as screen readers may not properly parse them.
Credits
Thanks to the University of Illinois Library Office of Information Literacy for permission to re-use elements of their guide, "Getting Started with LibGuides."