"To cook the noodles" means to prepare the noodles by heating them up, usually by boiling them in water, until they are soft and ready to eat. Full definition
These pasta dishes cook the pasta in the slow cooker so you don't have to go through the process of cooking the noodles in addition to cooking the rest of the dinner. (bembu.com)
Then cook the noodles according to package directions, usually boiling for under 5 minutes. (isachandra.com)
Turn heat off and add cooked noodles & peanut sauce to the pan. (thissavoryvegan.com)