What is the appositive phrase in the sentence: "Lenny, the editor of the magazine, cannot spell."?
The appositive phrase is the editor of the magazine.
The appositive phrase is a part of sentence adding some new information about a noun (in this case the subject).
The sentence would still be correct and make sense without the phrase but with the phrase it gives more information.
Without the phrase the sentence would be Lenny cannot spell. It is a correct sentence bot an appositive phrase makes it clearer.