After executing the code below, i get an ORA-25155 error
SELECT p.prod_id, prod_name, prod_list_price,quantity_sold,cust_last_name
FROM products p NATURAL JOIN sales s NATURAL JOIN customer c
WHERE prod_id = 148;
As suggested on a comment, this ORA-25155 error suggests that you're qualifying the column name "p.prod_id" instead of just "prod_id". That is what is triggering your error.
Try this fully working SQL Fiddle code. Your query should be:
SELECT prod_id, prod_name, prod_list_price,quantity_sold,cust_last_name
FROM products
NATURAL JOIN sales
NATURAL JOIN customer
WHERE prod_id = 148;
A NATURAL JOIN
over multiple tables will join one pair of tables, then join the third table to the result and so forth. NATURAL JOIN
syntax has no explicit join predicate, so the qualifiers aren't used there.