As a general rule, judgments and decisions issued by foreign courts cannot be executed in the Tunisian territory unless they are declared executory (i.e. enforceable) by the Tunisian courts that check if they comply with certain requirements.
Exequatur is not granted to foreign judicial decisions if:-
The subject of the dispute falls within the exclusive jurisdiction of the Tunisian courts.-
The Tunisian courts have already rendered a decision that cannot be appealed by ordinary means on the same subject, between the same parties and for the same cause.-
The foreign decision is contrary to public order within the meaning of Tunisian private international law or has been issued following a procedure that did not preserve the rights of the defence.-
The foreign judgment has been annulled, or its enforcement suspended in accordance with the law of the country where it was pronounced or is not yet enforceable in the country where it was rendered.-
The State where the judgment or decision was made did not respect the rule of reciprocity.
It would seem, therefore, from the little you have included, that the ex husband is trying to get the order agreed in Tunisia...however I would strongly suggest that you find a Tunisian lawyer who can read the original Arabic document so that your partner knows exactly how to respond to the court summons.