How to install languages in SugarCRM
By default, SugarCRM comes only with English. You can install and enable as many language packs as you want. You can find different language packs in the forge section of the official SugarCRM site.
After you download the language archive on your local computer, log in to your account in SugarCRM (as an administrator), then click on the Admin link in the upper right corner to open the admin panel. Scroll down the page to the section Developer Tools and click on the button Module Loader. On the page that opens click on the Browse button and locate the language archive. Then click on the Upload button to upload the archive to your SugarCRM hosting account. The language pack will be listed in the table under these buttons. Next to the name of the language pack there should be an Install button, so click on it. On the following page you'll be asked to confirm that you want to install the language; do it by clicking on the Commit button. If everything goes smoothly, on the next page you'll see a message that the installation was successful. Click on the button Back to Module Loader.
The language pack should be listed in the first table on the module loader home page. You can uninstall and disable the language by using the corresponding buttons. To see a list only of the languages that you have installed, and to enable or disable them, go to the home page of the admin panel and click on the button Languages that's in the System section.
For more details and screenshots you can also read the SugarCRM Languages Tutorial.