A Tenant in cloud computing terms is portrayed as an entity or organization or an individual who share common access that comes with special privileges, to specific software instances. So, a Tenant in Azure is labeled as a specific and unique organization that is listed in Azure Active Directory (or Azure AD), which receives and owns Microsoft Azure cloud instances and other services offered by Azure, that they receive when they sign up for.
If you wish to learn Azure and want to get skilled in it, to enhance your job prospects, then enroll in a good Azure course from Intellipaat, to help you optimize your practical skills. Watch a YouTube video on Azure Tutorial for Beginners if you are just starting out in the domain.