A proconsul was a governor chosen by the senate of Rome to rule a province. Starting from the time of Emperor Augustus, the Roman senate chose governors to manage certain Roman senatorial provinces. These were provinces considered safe enough that they did not need an army stationed there.
Proconsuls served for one year. They served between the time when they were a praetor (a lower government official) and when they became a consul of Rome (a higher position). Proconsuls were different from procurators, who were chosen by the emperor to rule imperial provinces for no set time period.
We meet two proconsuls in the book of Acts:
Sergius Paulus of Cyprus (Acts 13:7–12), and