It will display native PDF, but results are marginal, as you're trying to display a page designed for a full sheet of paper (A4/Letter) in an area approx a 1/4 of the size. If you *need* PDF, then maybe you need the iLiad or a tablet PC.
See
https://wiki.mobileread.com/wiki/PRS505 and
https://wiki.mobileread.com/wiki/LRF#LRF for more info on the Sony & it's native format. Note that you can download & install the various software beforehand to try & get an idea as to how things'll convert & look. (I.e. libprs500 - converter & viewer, Book Designer - converter, Sony's eBook Library - viewer)