To use windows 2012 as a print server you need to install Print and Document Services. Here are the steps on how to install Print and Document Services on windows 2012 R2:

1. Open Server Manager

2. Click Local Server in the right navigation pane
3. Under ROLES AND FEATURES click on TASKS and choose Add Roles and Features 

4. Next the wizard prompts you to verify the prerequisites have been met, click next

5. In next window Select Role-based or feature-based installation, and then click Next

6. Next check Select a server from the server pool, choose the server (the default is local server) and then click next 

7. Next select Print and Document Services, on the pop-up make sure Include management tools is check, and then click Add Features

8. Click next on features page 

9. On next page Role Services choose the desire services, by default only Print Server is checked, and then click next

10. Next review the selected option and click install to start the installation progress 
11. Restart the server to complete the installation