"Zij kon het bericht niet lezen, omdat het helemaal nat was."
Translation:She could not read the message because it was completely wet.
You can try the slow audio (the turtle icon) if it's difficult to understand the voice. Apart from that, I can only say, try to listen a lot, get used to the vowels and try to distinguish them. I understand it won't always be easy if you're a Dutch learner, but this sentence is very clear to my native Dutch ears.