What exactly does low AMH mean?

I have low AMH at 1.39 but I’m not quite understanding what AMH even is. Can someone explain it in simple terms and how it relates to <a href="https://glowing.com/glow-fertility-program">IVF</a>? Are my chances lower with <a href="https://glowing.com/glow-fertility-program">IVF</a> since my AMH is low? Thanks!!