Pace runs only make sense for long distances and you can find pace charts for the marathon, half marathon and 10k here.
A pace run in training is a run where you run the race pace for your target time but on a shorter distance. If you wanted to run a marathon in 3:30:00 you would have to run it at 5:00 minutes per km to achieve this goal. In training you take this pace but run it for the distance which is on your plan. So a 10k pace run for this example would mean running 10k in 50 minutes. Depending on your goals this can be the most challenging run in your training repertoire.
Always bear in mind that the longer you run, the more tired you will get. So if you can run 10km in barely 50 minutes you definetly can not run a marathon with the same average pace. I would say take at least one minute per km off that pace for your realistic marathon time as long as you do not imüprove in training.