The average time to run a mile varies greatly depending upon if you are Jim Ryun, Frank Shorter, or, well … you. Let's assume you are the latter: How long is it going to take you to pick 'em up and put 'em down for 5,280 feet? You can find out here, but you might not like the answer.
The reason Jim Ryun is mentioned is because he broke the record for the fastest mile in the 60s with a time of 3.:51.1. Frank Shorter won a gold medal in the 1972 Olympics for winning a marathon with an average of under five minutes per mile.
Now back to you. If you are a beginning runner in reasonable health, albeit out of shape, you should be able to average about twenty minutes per mile or less. That is about the time it would take to walk a mile at a reasonable pace. If you're averaging fifteen to twenty minutes per mile as a beginning runner, you are doing alright.
As you get into better shape, you can shave a lot off that time. Most beginning runners who are starting to get into good condition will run at an average of around ten or twelve minutes per mile. This is a reasonable pace for getting a cardio workout and dropping some weight. It doesn't stop there, though.
You should work toward a time of less than ten minutes per mile. One reason for this is that it will help you get into even better shape. Another is that you can burn more calories faster; you are covering more miles in less time. Yet another reason is that it is safer for the joints. The faster you run, the less punishment your knees and ankles take because your legs are not making as much contact with the ground. Instead of actually landing on your legs with each stride, you are essentially pushing away from the ground.
After you have become an experienced runner, you can certainly entertain yourself by pushing for six, five or even four-minute miles, but that is not necessary. If your average time to run a mile drops to seven or eight minutes, you are in good shape. You are running at a safe and healthy pace. Congratulations! Now hit the road.