Numerology's older texts frequently group 6 with domestic and communal themes — a household, a community, people who depend on one another. That grouping has held remarkably steady across different schools, which is part of why "responsibility" and "care" are almost always the first words attached to it.
Modern practitioner writing extends that into descriptions of 6s as natural caretakers, drawn to supporting family, friends, or a wider community, sometimes at real cost to their own needs. The traditional caution that follows is almost a mirror image of the strength: overextending, or defining worth by how much is being done for other people.
As with the other numbers on this site, this is a reading built up over generations of practitioner writing — consistent, but never independently tested.