I agree with the point Phil has made about "técnico". Although "technician" is the right translation in some contexts, it very often isn't. In English the word "technician" is strongly associated with engineering and technology, whereas "técnico" simply means someone with technical expertise in the broadest sense: someone possessing professional skills of some kind. An advertising technician implies someone who keeps the computers working, for example. A "técnico en publicidad" is simply someone with professional skills in advertising. So as a job, "técnico" is normally best translated as something like "specialist", sometimes "officer", or something like that. It's not a consultant, in any case. A consultant is someone who advises others on how to do their job; a "técnico" is someone who actually does the job at a practical level (so not a manager).

Here, however, it doesn't refer to a job, a post in an organisation, but to a degree. And in that context, "técnico" has other implications. It refers to a relatively short degree course of a primarily practical nature. In Spain, there is a distinction between shorter vocational degree courses called "técnico superior" and longer academic degree courses formerly called "licenciatura" and now called "grado".

The same distinction apparently exists in El Salvador. If you look at the degree courses available in the field of marketing and advertising, you'll see that some are called "Técnico" and others "Licenciatura". The former last 2 or 3 years, the latter 5:
http://www.universia.com.sv/estudios/marketing-publicidad/dp...

The course descriptions, though not very explicit, tend to support the idea that "técnico" degrees give people the skills and knowledge needed to work in the field (with some theoretical background but probably not very much), whereas the "licenciaturas" provide a fuller training (almost certainly with a much larger theoretical component) for people who will often go into management positions.

So I think that in this context "técnico en publicidad" means the equivalent of what is known in the US as an associate degree in advertising:

"An associate in advertising is a two-year program that prepares students for entry-level positions in advertising and equips them with the knowledge and skills required to pursue careers in advertising."
http://www.excite.com/education/business/advertising/associa...

In the UK the equivalent term would be "foundation degree in advertising".

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Note added at 17 hrs (2017-08-25 09:26:05 GMT)
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I forget to add that as you can see in the answer box I would retain the Spanish term "técnico" and add the English equivalent in parentheses. This is not essential, but I think it's advisable, since (as has been pointed out many times here in the past) equivalence in these matters is rarely exact, and the qualification is not actually an associate degree but the Salvadoran equivalent.