This is the 3144th most frequent Russian word.
личной
The Russian word "личной" means "personal" or "private" (feminine singular form).
In this sentence, 'личной' is an adjective in the instrumental case, qualifying 'историей' (story) and indicating it is personal.
Она поделилась своей личной историей.
She shared her personal story.
Here, 'личной' is an adjective in the prepositional case, describing 'папке' (folder) as belonging to personal items.
Я оставил это в своей личной папке.
I left it in my personal folder.
In this example, 'личной' is in the genitive case, modifying 'гигиены' (hygiene) and indicating the personal nature of the hygiene.