The point is that there are a number of symbols which we commonly know, but which cannot be consistently displayed on terminals or printers. On one, I was having difficulty finding some necessary punctuation marks for network addressing, and asked a Francophone programmer for help. Unicode seeks to address this problem. Including not only the variations on the Latin alphabet, Unicode incorporates Greek, Cyrillic, Hebrew and other alphabets. It also includes punctuation, diacriticals, mathematical and scientific symbols and miscellaneous graphics.
Asian ideographs are also assigned codes.
To comment on these in any meaningful way would be to rewrite these chapters. This is technical material, though not the same technology that computer types are used to. Some background study in linguistics would be a good idea, although it is not strictly necessary to understand and use the Unicode standard. There are, however, a wealth of symbols, punctuation marks and typesetting codes which Unicode gives standardized access to. On the other hand, any application which used the standard in a significant way would likely require a linguistics background in any case.