The man is on trial for bribery. The prosecution is likely to accept a cash settlement.
He is not admitting guilt, but with a guilty verdict meaning that the rest of the Formula One Group would have to remove him as CEO he must be pretty concerned that this is the likely outcome.
As GhostZ said, the Germans are in a tight spot with what to do with him if he were found guilty anyway; putting an 83 year old man in prison for 10 years (potentially/likely the rest of his life) helps nobody whilst $100m to the local government could really help people.
I can see the logic in it, but it feels absolutely absurd that you can end a bribery trial with a