The term "Enneagram" simply means 9-pointed diagram, which is a fancy word for the symbol. This symbol itself has deep roots in philosophy and tradition, but at it's core is a tool for self-awareness and growth.
There are 9 personality structures, or "types" that are recognized globally, across cultures, and religions, and are all gender-fluid. We are so much more than our type though, and as we learn about ourselves, we see that we are born in the box that is our type structure, and our life's work is the emergence from that box into the best, most full version of ourselves that we can be. It's a beautiful journey, full of color and richness, and I can't wait to join you on it!
The best way to determine your core type is to read all 9 and see which resonates most with you (not everything will apply or feel like “you”). That said, who has time for that? Here is a link to my favorite and most accurate free typing assessment. Take the top Classical test. Think of how you have always been (and not just who you are today). It may be helpful to have someone you have known for a long time take it with you to help you answer honestly. And, there are no “good” or “bad” types, so the more honest you answer, the more accurate your result.