Translation:The child does not look forward to the flight.
When do you need to add "er" in such a sentence? (with "zich verheugen"). I know you say: ik verheug me erop, but I don't get why here there is no "er", while in such a sentence like "ik verheug me er op om met je nederlands te spreken" you have to add it. (I thought it wasn't necessary because what I am looking forward to is already specified, but someone Dutch corrected me and said I should add the "er").
In this sentence, there is already a full prepositional phrase ('op de vlucht') in the main clause, so you don't need 'er'.
In the sentence "ik verheug me erop om met je Nederlands te spreken" , the part that is looked forward to, "om met je Nederlands te spreken", is a sub clause. When this is the case, you also need to insert 'er' in the main clause. The 'er' is there because the preposition can't stand on it's own in the main clause in these cases.
It's the preposition demanded by the verb verheugen. It's simply how the verb is used.