A more thorough explanation:

praepositus negotiis

A praepositus negotiis is a person who is put in charge of someone else's business.

• When the owner of the company went on vacation, he put his trusted employee in charge as the praepositus negotiis.
• The wealthy merchant appointed a praepositus negotiis to manage his trade deals while he focused on expanding his business.

These examples show how a praepositus negotiis is someone who is given the responsibility of managing another person's business affairs. In both cases, the person in charge is trusted to make important decisions and ensure that the business runs smoothly in the owner's absence.