An appositive phrase renames or describes a noun. It is extra information included to help clarify the reader something about the noun. In this sentence "an electrical engineer" helps the reader understand why the speaker's father is able to help her better understand the material in her science textbook. An appositive phrase is usually set apart from the rest of the sentence by commas and can be eliminated from the sentence without changing any meaning.
The closest meaning to the word congested as it’s used in this means when someone can’t breath because the this she nose becomes swollen that’s why is also called stuffy nose.
