A more thorough explanation:

Bona castrensia et quasi castrensia refers to goods acquired for military or quasi-military (i.e., public) service in Roman law. It was the property that a son could dispose of, by testament or otherwise, without his paterfamilias's consent. Paterfamilias refers to the male head of a family or household in Roman law, who had power over another.

An example of bona castrensia et quasi castrensia could be a soldier's salary or pension earned during military service. This property could be disposed of by the soldier without the consent of his paterfamilias. Another example could be a public official's salary or benefits earned during their service to the state.

These examples illustrate how goods acquired for military or quasi-military service were considered separate from the family's property and could be disposed of independently. This allowed individuals to have some autonomy and control over their earnings, even if they were part of a larger family unit.