If you want to give someone else full access to your course as an instructor, select Settings > Access, and then enter a list of email address(es) of the instructor(s) you want to invite to your course, separated by commas, semicolons, or spaces. Each instructor will receive an email invitation to join the course; the instructors you invite will have the same permissions that you do to access and administer the course, including access to all student data.
If you want to share the content of the course but not student data, you can provide a "copy code" to another instructor so they can copy your course. The copy code is found under Settings > Access. Anyone with the copy code can copy the documents, assignments, settings, and instructor comments, but won't have access to student data.