Something like below should help you.
select to_char(sales_date, 'mon') mnth, item_code, sum(sales_value) from sales_table
where sales_date >= add_months(sysdate, -1)
group by to_char(sales_date, 'mon'), item_code;
Please mark the answer as HELPFUL/CORRECT if it really helped you so that it can help others as well , help the community back
Thanks for your help on this, I knew it was relatively simple.