i need help with this

i sent my ipod for a repair because it has a one year warranty, so in the message they sent me it states

_+**If Apple determines, while inspecting your product, that service is needed due to the failure of parts that are neither supplied by Apple nor Apple-branded, Apple may return the product to you without servicing it, and may charge you the diagnostic fee plus applicable sales tax._**+

i really do not understand what it means.. plz i will be glad if i can get an answer