The core point of the parent comment was that the symbols become more composable, so you end up with vastly less of them to learn than the equivalent set you'd

The core point of the parent comment was that the symbols become more composable, so you end up with vastly less of them to learn than the equivalent set you'd have in a traditional language with shorthand spam from things like "reduce(+,x)" (or worse if you need a lambda around plus) being way too unwieldy and hard to read. APL has like 80 builtin glyphs, compared to hundreds or thousands of functions in stdlibs of traditional languages, and when you learn those 80, you can read & write all of APL (and the terseness means you can consume information much faster, and knowing all of the language vastly simplifies the writing process too - you might not need to learn all of a traditional language to read it, but writing one well still needs a very big coverage of knowledge, or constant docs lookup). Sure, for someone who knows C-like syntax, Java is infinitely more readable than APL, but if you bother to learn APL, it's pretty simple.