How?
You can mark text in a publication as being in another language. This enables you to hyphenate and perform spelling checks for text in multiple languages.
Note You cannot set mail merge fields, WordArt, or Web form controls as being in another language.
Mark portions of text
To reset the marked text as being in the default language, on the Edit menu, immediately click Undo.
Mark all text and table frames in a publication
To reset the marked text as being in the default language, on the Edit menu, immediately click Undo.
Note Any text that you add to the publication after this step will not be set as this language and it will not be checked automatically.