There are a number of ways to learn about Dynamics 365 and its family of products. Whether you are technical or business focused, a solution architect, developer, product owner, business analyst or QA/tester. Microsoft and the community have a wealth of material available for you to discover and explore.
Here are a few reference points I recommend for you.
You can see further training details on Microsoft Docs regarding Dynamics 365 Training. For developers, Microsoft Docs also hosts a number of other useful resources.
if you choose to get certified in Dynamics 365 then read about this on the Microsoft Learning Website MCSA in Microsoft Dynamics 365