Fanaa (Sufism) is a big word that is used to describe a very special feeling that some people who follow Sufism religion have. It means "annihilation" or "total surrender" in Arabic.
When a person meditates and prays a lot, they may reach a point where they no longer feel like they exist as a separate person. They feel like they have become one with everything around them, with the universe, with God. It’s like they become part of something bigger than themselves, and they lose their individuality.
It might be a bit like feeling like you’re in a big bubble and everything around you is part of that bubble, including you. You can't see where the bubble starts or ends, but you know that you’re inside it. You feel safe and happy because everything is connected and you’re not alone.
This feeling of fanaa is considered to be a really powerful spiritual experience. It helps people to let go of their worries and be at peace.