Consul was one the highest elected political office of the Roman Republic and the consulship was considered the highest level of the Cursus Honorum: which was a way of public office which a people who are looking to be politicians to ascend.
How does it work there was two elected consul each year to serve one term. The consul would take turns in holding imperium each month and the consul imperium would extended over Rome, Italy and various other provinces. The establishment of the empire the change of the Consul power and role relatively was a figurative representative of the Rome and republican heritage which the consul has little and no authority. Which the empire powers the sole leader of the empire.