It literally translates to "on the page", referring to being featured in a fashion magazine or being "in the news" as it were.
Here are some examples of how it's used:
* "Cette robe est à la page." (This dress is in style.)
* "Le nouveau look de Beyoncé est à la page." (Beyoncé's new look is fashionable.)
* "Ce restaurant est à la page avec son menu." (This restaurant is fashionable with its menu.)
It's important to note that "à la page" can also mean "up to date" or "current" in a more general sense, but it is most often used to describe fashion and trends.