Most of the Perl code you'll write will deal with text files only rarely will you have to deal with binary files.

Even if you need to deal with binary files, most likely they will be of some standard format, e.g. an image, a zip-file, an excel file, etc. For most of the standard formats there are specialized libraries that can read and write them. So you will have high-level abstraction and you won't need to deal with the binary files directly.

Nevertheless it might be useful to take a quick look how binary files can be handled in Perl.