Here's why:
* Homographs are words that are spelled the same but have different meanings and sometimes different pronunciations.
* Homophones are words that sound the same but have different spellings and meanings.
Content has two main meanings:
1. Satisfied: "I am content with my life." (pronounced with a short "e" sound)
2. The things that are in something: "The content of the book is fascinating." (pronounced with a long "e" sound)
Since "content" is spelled the same in both cases but has different meanings and slightly different pronunciations, it's a homograph.