Can someone help me understand why this chart is so important?

Izzy • PNW 🌲 Retired Professional Ballerina. Master Pointe Shoe Fitter. Momma to 🐕🐈 👶🏻💙
Hello ladies!!! I am new to TTC and I am having one heck of a time understanding what is going on with this chart. Any help is super duper appreciated! ✨Baby Dust to all✨