Here are the steps for Internationalization:

1)Enable Translation Workbench. 

Translation Workbench is a salesforce tool which lets you translate labels used on Salesforce UI. To localize labels you will have to enable this feature which is mentioned in the link below.

2)Export Import Labels

Once you have enabled it, you will have to export labels download it to your desktop. Once you have downloaded labels, you add translated values corresponding to labels save the file and import it back to salesforce. Detailed steps are mentioned in the link below.

Enable Translation Workbench & Language:  Click Here

Export Import Labels:  Click Here