cubase ai5

I soon will have a yamaha product that comes with cubase ai5. I have been watching numerous videos regarding music mastering. All tbe videos that I have seen, they all use external software (eg Limiters and Maximisers etc) and not whatever comes in cubase to master the recordings… Could someone please tell me what mastering software is in cubase ai5? And if it is any good as they use other stuff to master thier recordings? Will I have to get other software (ie PSP Xenon) or not? Thank you in advance for any responses!! Regards to you all