username wrote:and here "What" is in fact the subject of the sentence
I don't believe it is. There are two clauses in the sentence: in the first clause, the subject is
The course, for which the verb is
aims; in the second clause, the subject is
core ways of conceptualising globalization and globality (or, if we were to get rid of the modifiers and such,
ways), for which the verb is
constitute. And as you mentioned, the subject and verb must agree, so that is why
constitute should be in plural form. In this sentence,
what functions as a conjunction joining the two clauses because it has the meaning "that which," and conjunctions do not determine the type of verb.