Can I rename "courses," "lessons," "topics," and "quizzes"?
Yes, you certainly can.
Go to LEARNDASH LMS > SETTINGS > ADVANCED > CUSTOM LABELS to add or update the labels.

After you are done adding all custom labels, click Save in the Save Options box on the right.

When you apply custom labels to replace the default labels, all references to those labels will change across the WordPress admin area and on the front end of your site. These changes will be visible to all users, including site administrators.
Adding the custom labels will not change the permalinks automatically. Our guide here explains how to change permalinks.

If you would like to revert the labels back to their original versions, click Reset Settings at the bottom of the page.
NOTE: Any text not included in the Custom Labels section can be modified using the translation files. To do this, you’ll need to edit the current language file and look for the text you want to change to update the label. For detailed steps, please refer to this documentation: LearnDash Translation Guide.
FOR MORE CUSTOM LABEL INFORMATION: Please see our full documentation on custom labels.