And it's the second sentence for a illegal financing of his presidential campaign.

Formal proofs of this illegal financing have been linked to two of his closest collaborators but not him directly. He is so convicted for "association de malfaiteurs" wich mean "partnership with criminals / wrongdoers".

The illegal financing also explains what the US call the "Sarkozy war", which what a very odd move from France.

Note that, despite the formal proofs of the wrong doing, Sarkozy has the support of most major medias AND from the current president Macron which is not exactly the same party as Sarkozy (but close enough). That suggests politically motivated prosecution is very unlikely.