This is one of the most used tools when coaching athletes, estimating your own time, or goal setting. You can input a recent race time and it will tell you the pace of your effort, equivalent times, and estimated training paces.
Everyone is different and you need to take some of the results with a grain of salt. For training paces and equivalent efforts It's not definitive, but rather an estimation. Also, the further you get from a set distance, the less accurate it will be. For example, if you input a mile time, it may list the equivalent effort in a marathon. That doesn't mean you can run that time - it's just stating what a comparable effort would be in a marathon.
Nonetheless, if you have two distances that are close together and have similar training, it can be useful. If you just completed a 5k and are looking to set a goal in the 10k, you can get a fairly accurate idea of what is a decent goal to set.