The 12th house is a closed house, a house of seclusion, immersion into oneself, into one's inner world. And here, the activity of a person in a closed house, behind a screen, is hidden. But this does not mean that a person is inactive and lies on the couch all day long... Absolutely not.
There can be several options here. A person may work, but likes to be alone, it is more comfortable for them, they work better. A person may have a job, but does not advertise it, hides it from most people. May work without official paperwork. Possible work abroad.
The option that a person works in a closed organization, may work in hospitals, in prisons. And sometimes a person works and has double accounting.
Such a person has the ability to do everything through other people's hands, as if from behind the scenes. They can organize well, twist everything in space, but prefer to stay behind the scenes. There is some manipulativeness in their actions.
In a woman's chart, it may indicate a man who is far away, may be abroad, or is constantly on business trips, or a man who is constantly hiding something. And here there may be some closeness, both on the part of the man and the woman, that is, they may not be completely honest with each other.
It may be an indication of secret enemies. That is, a person feels some kind of envy towards themselves, some kind of unkind looks in their direction. Or they may feel some intrigues around themselves.
With a damaged Mars, it may be an indication of criminal activity, but we understand that one indicator is not enough for this.