Two solid black bands around the arm usually mean whatever the wearer intends.
Most common: mourning/remembrance of lost loved ones (classic black armband tradition; two often for multiple losses), strength after hardship, life transitions, or just a clean minimalist look.
In some LGBTQ+ online circles since the 2010s it's memed as a "depth marker" for fisting. That's the viral NSFW joke behind the "run away" posts—but tattoos aren't secret codes. The person decides the real meaning.