This is the 8538th most frequent Russian word.
о
"О" means "about" or "concerning."
Here, 'о' is used to indicate the object of the thought, showing what or whom the action pertains to.
Я думаю о тебе.
I am thinking about you.
In this context, 'о' specifies the subject or topic of the story, clarifying what it pertains to.
Это история о герое.
This is a story about a hero.
Here, 'о' indicates the topic of the conversation, explaining what the speech is focused on.