Several different types of snb to pdf conversion exist, but all of them are doable and are about document / publication conversions.
Exporting S Note notes to PDF
A lot of Galaxy Note users try to export their notes( saved as .snb files) to something more common like PDF. The easiest way here would be to download the S Note software for desktop, import your .snb files in it and export it as a PDF document.
Exporting Shanda Bambooks to PDF
SNB is rather rare digital book format and not widely supported, however some ebook management programs support it and can be used to export it to something more common, like the PDF document format, which basically represents a way to convert snb to pdf as well.