Return type of @@LANGID function is smallint.
Examples of @@LANGID Function :
Example 1 : Use of @@LANGID function in select clause
SET LANGUAGE 'ENGLISH'
SELECT @@LANGID
Output
0
As you can observer that you can set language and if you execute @@LANGID function it shows identifier for current language in use. In above example it shows id '0' for 'ENGLISH' language.