Read this. Please go back and edit your post in line with that link.
It means it can’t be reassigned within the method. If they have gone to the trouble of marking the second parameter (not argument) final, why haven’t they marked them both final? I cannot explain any more with the information I have been given.
If you think it means you can’t alter the original value of the argument (not parameter), you have not understood pass-by-value.
Since English is not your native language, you may not be aware of it, but that sounds bossy and rude. Simply adding the word "please", or phrasing it as a question, such as, "Could someone explain it?" would make it more polite.
Also, you need to be clear about what you don't understand. Don't make the mistake of thinking these forums are a substitute for you spending time--a LOT of time--researching, studying, reading, thinking, getting frustrated but continuing to work on it, writing code, etc.