GNU/Linux Ubuntu 20.04 Realtek rtl8723be Driver Installation Guide
How to Install Realtek rtl8723be Wireless Driver for Ubuntu 20.04 Focal LTS GNU/Linux – Step by step Tutorial.
The Realtek rtl8723be Ubuntu 20.04 Driver should be already bundled into the Linux Kernel.
But if needed as a replacement see the Realtek rtl8821CE/rtl8192CE Driver Setup.

Installing Realtek rtl8723BE Driver for Ubuntu