We can import a NetSuite Translation collection string by using the navigation:
Customization > Translation > Manage Translations
Under the ‘Strings’ subtab and ‘Import Jobs’ subtab, you can see the ‘Import Translation’ button. On clicking the button, you will get a pop-up where you can select the XLIFF file to be imported.
On importing a translation collection to a new account, the strings will be attached to the custom collection referenced in the file.
You can see the running import jobs and history under the ‘Import Jobs’ subtab.