“Enharmonic equivalence” means writing a note of the same pitch in different ways, e.g. F# as Gb, or B as Cb.  You are almost bound to get a question on this as part of question 1 or 4

1 (a) (ii) Write as a breve (double whole-note) an enharmonic equivalent of the first note of the extract.

Look at the model answer

Very occasionally you might be asked to rewrite an extract in its enharmonic equivalent key, changing the key signature, e.g. rewrite a piece in C major in the key of B# sharp major!  They wouldn’t pick C major though! Almost always they pick the enharmonically related keys at 6 o’clock in the cycle of fifths (i.e. keys with 6 sharps and flats).

4 (b)  Re-write this extract in its enharmonic equivalent key.

Look at the model answer