While you didn’t mention a male, I am sure you realize the eggs will not be fertile and hatch unless she has a mate. If she does have a mate, it sounds like she has done what is called double clutching – when they lay two clutches at the same time for unknown reasons.
The incubation period for parakeet eggs is 17 – 21 days. The countdown does not begin until she actually begins to sit on the eggs. Generally this is when all of the eggs are laid, but sometimes sooner. It could be the first four are not fertile but the next four still may hatch. Do not do anything with the eggs until at least a week after the 8th egg would be due to hatch, counting from the day it was laid since she was already sitting on them at that point. If they don’t hatch, there can be a lot of reasons – infertility of one parent, poor incubation, wrong humidity, poor nutrition, young birds, old birds. Really there is no way to know for sure.
If these eggs are not good, remove her nest box when you take the eggs away. She needs a good rest so do not set her up for nesting again for at least six months.
Meanwhile, you might want to do some additional research on breeding parakeets/budgies. There is a lot involved beyond just giving them a nest box. They need the right environment, not too dry or too wet, extra foods, privacy and patience on your end. And some birds simply do not produce chicks. Breeding is not easy and the waiting truly is the hardest part.