Yes, bobdoering has given a great link.
SG & A is a tool to analyse an Income Statement.
SG & A expenses consist of the combined payroll costs (salaries, commissions, and travel expenses of executives, sales people and employees), and advertising expenses a company incurs. High SGA expenses can be a serious problem for almost any business. A good management will often attempt to keep SGA expenses limited to a certain percentage of revenue. This can be accomplished through cost-cutting initiatives and employee lay-offs.
More at
http://beginnersinvest.about.com/cs/investinglessons/l/blsga.htm