GNU/Linux Mint 20 Installing Broadcom BCM4311/BCM4312/BCM4313 Driver Guide
The linked tutorial shows you step-by-step How to Install Broadcom BCM4311/BCM4312/BCM4313 Wi-fi/Bluetooth Driver on Mint 20.x Ulyana/Ulyssa/Uma/Una LTS GNU/Linux – Step by step Tutorial.
The Package Provides the Source Code for the wl Kernel Modules and makes use of the DKMS Build Utility to Install them for the Running Kernel.
GNU/Linux Mint 20 Broadcom BCM4311/BCM4312/BCM4313 Driver Installation Guide