Well, there is probably no need to explain what ethics in advertising is as the term is self-explanatory. The idea is that there are certain moral principles which a person adheres to when they are making ads. In other words, some people will never cross the line trying to offend other brands so that to show how great their brand is compared to the other one.
Apart from that, this term also stands for the ability of the advertising company to present true information to the customer. In other words, the ad will not lie about the quality of the price or their price. Thus, behaving ethically in advertising says a lot about the company that is producing that ad.
There is no doubt that ethics and principles depend greatly on what the person believes in. Thus, they may be a little bit different depending on the person but the general idea is that there are things which a person will not do no matter how much money it may bring.