The word "ego" can have multiple meanings, depending on where you've heard it.
I first learned it as a synonym for "arrogance."
But from a psychological and spiritual perspective, the word "ego" refers specifically to the collection of unconscious internal instincts within the human mind.
I have an ego, you have an ego. Everyone, from the nicest people to the surliest, has an ego.
Egos get a bad rap, but they actually have a very worthy purpose: to keep us alive for one more day.
That short description is the entire scope of the ego - just survival, and just for the next day...
...which is where the challenge lies, because your dreams and aspirations are much bigger than that right? You don't want to just survive, you want to THRIVE!
Perhaps you dream of travel, or material abundance, or positively impacting the lives of others. Your ego will let you have those, but only so far as they don't interfere with its far more primal goal of survival for you.
The moment that any of your aspirations threaten what you ego believes is necessary for your survival, it will assert its dominance in a way that interferes with your goals.
Have you encountered that yet - an experience where you got in your own way of your own desires? When that happens, it's because your subconscious ego instincts perceive something about your goal (or what it takes to achieve it) to be unsafe for you.
Any effective spiritual training will give you countless opportunities to meet your ego - that is, to see it in action in a context where you can recognize what's going on.
The goal of such a training isn't to destroy your ego but to grow it up. By default, the human ego stops evolving at age 12, when you've learned everything you need from your parents in order to survive. And without some process that directly addresses your ego, age 12 is where it will stay.
This means that by default, nothing you've learned from age 13 and beyond - not even all the teachings about spiritual laws, abundance, etc. - has any influence on your ego's sense of what it takes to survive. Simply absorbing information does nothing to alter the primal instincts of the ego. It doesn't matter how many books you read, how many classes you take, how many psychic readings you give or receive; your ego will let you receive that information but will not be influenced by it.
Your ego is not changed by information. It is only changed by experience.
That is why an experiential program is vital to mastering your life, because it's only through real experiences - not sitting in classrooms and workshops - that you can learn through experience how to recognize your ego's behaviors and retrain it to behave in according with your desires.