Learn Russian: Женщина часто рассказывает о нём.

After the preposition о (about), Russian requires the Prepositional case. The basic word for "he" is он. In the Prepositional case, the root changes to ём, and because it comes right after a preposition, an н is added to the beginning to make it easier to say. So, о plus он becomes о нём.

Why does this sentence use о instead of об?

You use об when the next word starts with a vowel sound (like а, о, у, э, и), which makes it flow better when speaking. Since нём starts with the consonant н, we just use the standard о.

I learned that говорить means "to talk". Can I use it here instead of рассказывать?

Yes, you can! Женщина часто говорит о нём is perfectly fine and means she speaks about him in a general sense. The verb used here, рассказывать, means "to tell" or "to narrate". Using рассказывает implies she is sharing stories or specific details about him, rather than just mentioning his name.

Could I put часто at the end of the sentence?