Sales by month cross tab query using pivot
Since your new columns are numbers, you need to escape the names with square brackets:

select ShippedYear, 1 as Jan, 2 as Feb
from
(
    select  datepart(year, ss.SHIPPED_DATE) as ShippedYear
          , ss.SHIPPED_AMOUNT as Amount
          , datepart(month, ss.SHIPPED_DATE)) as MonthCode
    from    dbo.SALES_SHIPPER_LINE ssl join dbo.SALES_SHIPPER ss on ss.ID = ssl.SHIPPER_ID
) ps
pivot(
    sum(amt) for MonthCode in ([1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12])
) piv;


The square brackets [] are used to delimit identifiers. Since the column name begins with a number, this must be delimited. See MSDN for more details.