I will add my best unsolicited advice to this. If you do not understand what a marketing or advertising professional is telling you and you ask them to explain

I will add my best unsolicited advice to this. If you do not understand what a marketing or advertising professional is telling you and you ask them to explain it further and it still does not make sense—lots of jargon, buzz words, and “secret sauce”—do not hire that person. There is nothing in marketing that is so conceptually difficult to understand that it cannot be explained at a high-level to a lay person. If they do not explain it well they either A. Do not understand it well themselves, or B. Do not want you to understand it. Also be wary of big promises up front. No one can actually promise XX% increase or XXX more leads without having advertised your specific product before. They might be able to provide a general estimate based on past experiences, but that is it. Best of luck.