Please enlighten me, while visiting profiles, I'd notice a bright star on one user's profile , it's shining next to the blue icon (verified mobile number), what does it means and how one can acquires/earns for it?

Thank you in advance.

It means that user is in your Favorites.

Whenever you add a user to your Favorites, their username will display a star when you view them anywhere on the site to remind you that they're one of your Favorites.

Each user will only see the star on users they have personally Favorited.

Once again, thank you :)