Annoying split screen
How do I eliminate the split screen In mail and safari?
iPad Air 2 Wi-Fi
You may find these overview Apple video guides to be helpful:
After viewing, you’ll be ready for the additional Multitasking Guide:
Use Multitasking on your iPad - Apple Support
The iPad User Guide for iPadOS is also a rich source of information. Here are links to both the downloadable and online versions of the Guide:
iPad User Guide on Apple Books
iPad User Guide - Apple Support
I hope this explanation and additional information is helpful in resolving any difficulties you may be having with Multitasking features of your iPad.