well I have been in the bar business for a long time so I will help you out here. As stated above your the grunt worker. You take out trash, wash dishes, get ice, restock etc. Now for males this is usually the only way to become a bartender. I personally have never hired people that went to bartending school. They are usually not very fast at their job, just good on presentation. Now if I were to run an upper end Martini bar they would be who I would hire. However for a high volume bar I take the people with the experience, and look I need. Now a days male bartenders are getting few and far between. The last two bars I have run were around 80% women on the bartending staff. Women do not usually need to barback before they become bartenders although I have seen that before. Women usually waitress first. I am not trying to be sexist here I am just stating what actually happens.
You can make a little extra money barbacking depending upon were you get a job and it is good experience to have if you ever wish to get into bartending which can be very lucrative. It is how I helped pay for my education without taking out student loans, but after I got my degree in accounting I stayed with the bar business and moved up to running night clubs. The money in this industry is fast and easy and usually payed that night. The biggest problem people have in my industry is that they never save money and spend it as fast as they make it. I chose the other route of investing it and saving it. I for one can say this industry has been great to me. I have no debt at all, a good bit of money in the bank, a long running mutual fund that will help me to be completely retired by the time I am 45 or 50 and live compfy. I also have a reconstructed nose, two false teeth, and had a fractured skull from getting hit with a sawed off baseball bat trying to break up a fight outside the first bar I ever managed so its not all roses and dollars, but for me its a living.