In that case, all I can suggest is you ask the school!
It isn't a specific subject, well not in any school I've ever heard of. The only think I can think of is that the school may be referring to extra-curricular activities, or perhaps extension work where the student does more than is required, as "Enrichment", but it does sound a bit too much like "marketing-speak" for anyone but the school to explain exactly what they mean. I suppose it could even be that the student is learning how to offer enrichment in a teaching capacity, but I'd only be guessing. Sorry.