What @jrichard326 said, and if it still doesn’t work, please see, [HowTo] Provide System Information and, if applicable, [HowTo] post screenshots and links
Edit:
And, in addition to what @jrichard326 said, I’d recommend you rather use the -dkms
driver, as this survives kernel rebuilds. And it seems to be available in the community
repositories:
$ pamac search broadcom
[...]
broadcom-wl-dkms 6.30.223.271-28 community
Broadcom 802.11 Linux STA wireless driver
So, should theoretically be installable with:
pamac install broadcom-wl-dkms
Or, that’s the theory, anyway.