Well, they are either letters or numbers. What they mean depends upon what they represent. Is it binary code, text, data, what? Until you know what it represents, understanding them is impossible. Some sequences of non-text data are known, and you can then determine what they are, and then decode them. If you determine the values are program code, then you can use a disassembler to turn the hex code into assembly code. If not, then the problem becomes much more difficult as the hex may represent encrypted data, which is another problem entirely.