25 minutes is a fair time for someone your age and who has only been running for 1 month. If you really get into it then you'd probably want to aim for about 18 minutes which would be competitive at a local level, but take it bit by bit, it takes a lot of training to get to that level, especially if you haven't been near that before.
I'm about 2 months into getting into running again and my 5k pace is currently 21 minutes, 10k is 48 minutes though I could probably do ~46 on a better day.
Try to do a combination of running further than 5k on some days and running faster than your previous pace on others. Make sure to do more exercise than just running as this will help too, even if this is just sit-ups, press ups, squats after your run.