It's essentially a loan but quite a neat structure whereby Barcelona are able to both offload Bojan's salary (which I can't imagine is huge) AND recognise the gain on selling the player.
Now it really only works well financially (in the context of FFP) in the case of a player who has come through your academy system (so who has a cost of nil in your books). In such a case the 12m is pure profit and inflates your results for the year in question for the purposes of FFP.
Now because the option to buy Bojan outright is 28m (in addition to the 12m already paid) the likelihood is that Roma will not exercise the option unless Bojan absolutely sets the world alight.
If Roma don't exercise the option then Barcelona are obliged to buy back the player for 13m.
If he is bought back in such a manner and given (say) a five year contract then his salary obviously comes back onto Barca's books but the 13m cost of the player will be spread over the term of his contract....so 2.6m per year.
So basically Barca get to inflate their profits by the whole transfer fee in the year he leaves....but when he is bought back their yearly results are only hit with 1/5 of this amount over each of the 5 years of his contract.
Quite neat but it would only really work for academy players where they have nil cost in the books AND you can command a worthwhile fee that will make a suitably juicy contribution to profits in the year of sale....
