So we have been having an issue with one of our fuses keeps blowing. It's the same fuse and its blown about three times within two weeks. My brother told me to get one of those receptacle testers so I did. I tested every outlet today and they all say "open ground". Can someone please tell me what that might mean and what should I do to fix it.

In this case I would recommend having a qualified electrician or the power company to look at. Depending on how things are wired, it probably should be the power company.

This is a "very unsafe" condition and even fiddleing with the ground bond can be disastrous for your electronic equipment.

There is a ground-neutral bond somewhere that's broken:
1. It can be in the breaker box
2. It can be in the meter base
3. It can even be on the pole/transformer

Call the utility ASAP.

How many wires go to each receptacle box and what color? You may just have no ground in your circuit, common a very long time ago. The blown fuse likely has no relationshp to the open ground.

I agree with ballenger on this. The fact that you have fuses instead of circuit breakers tells me your house is fairly old. Older homes were frequently wired without grounding wires on the circuits so it likely is not the cause of your blown fuses.

What size circuit is it and what is on it? Did you recently make any changes to what is plugged in or where? Did you buy any new electronics or appliances?