Please try below:
DECLARE @Today DATETIME;
SET @Today = '12/5/2007';
SET LANGUAGE Italian;
SELECT DATENAME(month, @Today) AS 'Month Name';
SET LANGUAGE us_english;
SELECT DATENAME(month, @Today) AS 'Month Name' ;
GO
Reference:
https://docs.microsoft.com/en-us/sql/t-sql/statements/set-language-transact-sql