Preeclampsia..?

Haley • Mommy to two amazing babies❤

I am currently 25 weeks 4 days with my 3rd child, my other two pregnancies were both healthy, no complications whatsoever. I went to the doctor yesterday for a standard check up with my baby and was told my protein in my urine was 300, she told me not to stress yet, but that's extremely stressful. I do not know much about what Preeclampsia even is, has anybody had it? What should I expect?