Absolutely YES. Java EE is used everywhere by large multim=national companies who build enormous robust systems to small dynamic start-ups that love the microservice architecture.

There are a plethora of online learning resources, free and paid, that will teach you everything you need to know about the multitude of APIs.

Go to youtube, go to Lynda.com and go to Pluralsight.com, there you will find all the resources you need for free or very little cost to learn Java EE.