This one also surprises me that someone has not already posted.
The TD_Month_Of_Year function returns an integer value that need to converted to string value. Careful when using this on a large data set, it can really slow down the response time.
select td_month_of_year(current_date), CASE td_month_of_year(current_date) WHEN 1 THEN 'January' WHEN 2 THEN 'February' WHEN 3 THEN 'March' WHEN 4 THEN 'April' WHEN 5 THEN 'May' WHEN 6 THEN 'June' WHEN 7 THEN 'July' WHEN 8 THEN 'August' WHEN 9 THEN 'September' WHEN 10 THEN 'October' WHEN 11 THEN 'November' WHEN 12 THEN 'December' END AS "Month of the Year"
Note: If you know of a native Teradata function that does this, please leave me note in the comments.