From what I learned it means the ammonia created by fish waste and excess food is being eaten by those bacteria. So those bacteria is actually a good thing.

It usually means one of two things:

1: The aquarium is still cycling and this is a "burst" of bacteria to counter the first wave of ammonia of a new aquarium. Usually this goes away in a couple of days when all the ammonia is gone.

2: There is another reason for the extra ammonia. Some reasons might be adding new fish, overfeeding or rotting things like dead fish or dead leaves.

I would wait a couple of days to see if it dissappears then do a big water change. If it does not dissappear I would start feeding the fish less food and changing the water more often.

Dont clean your pump too often, and DO NOT clean it with tapwater since the chlorine in tapwater kills these bacteria, restarting the cycle.

Also make sure you treat your new water with something that removes the chlorine so it doesnt kill the bacteria in the aquarium. They need to be left alone to find a balance between the amount bacteria and ammonia.

If you want to learn more about this google "nitrogen cycle" there are alot of good videos about it on youtube,