Option 1) If you'd like to find out the nameservers your website domain you've purchased is using like yoursite.com then you can just check easily using this link below
Type in your website address like I have done and click search
It will then list two lines beside each location of what nameservers it finds.
Option 2) You have your domain registered and purchased and you need to find the nameservers to use for getting your site online!
Visit www.000webhost.com if you are using the free hosting, hit manage website once logged in and then set web address.
Clicking add domain at the bottom will reveal this wizard and it will tell you more than likely your website needs to point to ns01.000webhost.com and ns02.000webhost.com
If you have gone to premium hosting then you can find the nameservers easily within your control panel or contact support via ticket/live chat if you can't see them. http://hostinger.com