Hi! 

"Garson sorusunu cevaplıyor."

I know this is saying that the waiter is answering his/her questions. However I am confused at what the -nu is implying? If someone could tell me the forms and meaning of this suffix that would be splendid!

You have the meaning right. 

soru + su + n + u

´nu´ isn´t a suffix per se. It´s the ´u´ noting the object, i.e. the thing you are asking. And ´n´ is a buffer letter. This link explains a lot of this - #2 Object condition http://www.turkishlanguage.co.uk/suffix.htm . It is required for certain verbs.

OH! ok I understand. So by adding the -u they are making it a specific question. Thank you!

OH! ok I understand. So by adding the -u they are making it a specific question. Thank you!

OH! ok I understand. So by adding the -u they are making it a specific question. Thank you!

Yes, it´s a bit like ´a´ and ´the´ in English:

Here you don´t add u:

Tom asked a question.

Tom bir soru sordu.

Tom dün sorduğu soruyu tekrar sordu

Here you see it again

Wait why is the buffer letter y now?

Yes it is a little tricky. For the first suffix it´s (y)i. For 2 or more, it´s (n)i.

Here i is the first suffix:

I like the car. O arabayı seviyorum.

Here i is the 2nd suffix:

Tom likes his car - Tom arabasını seviyor.