you can easily forget about learning a full programming language like C+, you wont need it.

Scripts and programs are the same thing; lists of instructions. The difference is that a script controls an OS, giving it complex instructions eg moving tagged or named files from one place to another. A program is a list of lower level instructions that by comparison, creates file structures, reads and writes data bytes and performs complex mathematics.
Programs often have interfaces too, where scripts do not, although this is not a definition, just a convention.

All script languages should be able to to anything the OS can, so choosing one is a matter of preference. The author mentions Perl, however Ruby is more usually installed on a Mac or Windows, and Linux will often have both.

However, I'd recommend Python, because it runs on everything and is simpler to learn in my opinion. It is also more 'OS agnostic' than the others, behaving the same regardless of the host OS. This is helpful when googling how to do something; you will get one approach instead of 2 or 3 different ones.