When SEOs consider adding keywords, they often think back to the days of stuffing keywords into the meta tag or overreacting each one in the text of a page. Things have changed a lot today!
When writing your GMB description, it's important to understand that keywords are generally considered to have no impact on your local rankings. So you don't need to stuff your description with keywords. That said, it's worth taking the time to read Google's guidelines to avoid mistakes that could lead to your listing being suspended.