Wi-Fi 6, otherwise known as 802.11ax, is an improved generation of wireless communication between devices. Both client and router need to support Wi-Fi 6 to get its benefits, but these include faster throughput for a more stable and efficient connection, (ideally) less interference, and upgrades to MU-MIMO features.
Wi-Fi 6E delivers the benefits of Wi-Fi 6 with the 6GHz frequency in play to expose further congestion-free networking to your compatible devices. You probably need a good reason to buy a Wi-Fi 6E router today, but it could offer you some improvement with compatible devices.