van2z work profiles are kind of like secondary user profiles, which are for different identities or uses. Like, for example, if multiple people use the same phone, use profiles. Also, if one person uses the phone, they an use profiles to separate work and regular life. Many GrapheneOS users use profiles to separate apps depending on whether they require or rely on Google Play.
I personally don't use a work profile, but I read that some people prefer them because they can do one or both of the following things: shut down the work profile whenever they'd like and/or have two instances of the same app at their fingertips (for example: personal Signal and work Signal).