Ancient Rome was characterized by physical features like the Tiber River, the Alps mountains and the Italian peninsula, though the Empire eventually expanded to include land across much of modern-day Europe. Some of Rome's most important physical features, including the Alps, helped give the Empire an advantage over competitors.
When discussing a location, physical features refer to the geographical and natural formations and characteristics of that place. Ancient Rome's physical features include all of its natural characteristics, such as its proximity to the Mediterranean Sea.
In many ways, Rome's physical features helped the Roman Empire succeed; its proximity to the Mediterranean Sea allowed them to trade and interact with other civilizations, and the Alps helped protect the city of Rome from attack (with the famous exception of Hannibal).