I use it mainly to help others by sharing missing people and pets, local problems eg road closures, accidents, burglary locations etc. Also recalls of food or other products. Sometimes share gofundme pages for good causes too.
I keep in touch with family and friends with FB messenger which is more private. Also sell and buy a few thing on FB market place.
I never put personal details on there eg when I'm off on holiday, photos of dogs and DGC, when I'm out shopping etc. This is high risk. Don't have anyone I haven't met in person as a friend either