I have been using vlookup for many years, but now need to move onto index match that returns multiple values. But this seems a bit complicated for my Excel knowledge. So I am looking for a "mickey mouse" explanation around this sort of formula:-

=IF(COUNTIF(Materials!B2:B21,D2)<ROWS(A$1:A1),"",INDEX(Materials!B2:B21,SMALL(IF(RangewithNames=SpecificName,ROW(RangewithNames)),ROW(A1))))