My deck was becoming faded from the sun and starting to become dried up. So
I just power washed and stained my deck with an oil based Semi-Transparent
stain from BEHR.

The stain claims to be "Water Resistant".

Does this mean I have to apply another coat of a water sealant? Or does
Water resistant mean I "don't" need anything else?

The wood is a pressure treated if that helps.