Literally translated as gaining some bottle the expression illustrates the fact that a person gains value, experience, or wisdom with age. Along the same lines, avoir de la bouteille means to have acquired experience, to be an old hand. The expression is mostly used figuratively to describe people. At a basic level, however, you could use it to indicate that your favorite bottle of wine has been aging nicely in the cellar.
Originally, prendre de la bouteille was only used in regards to the aging of wine and other spirits, indicating that they had spent a number of years inside a bottle, as opposed to the casks or barrels of their young days. It was not always meant as a good thing then: not all wines benefit from aging, and even those that do will eventually fade if aged for too long.
Although you could say the exact same thing of people, the idiom took on a generally positive implication when it crossed over to humans in the late 19th century, focusing on the good things one gains with age. It can still be used to talk about wine, but again, in a positive light.
L’entretien s’est bien passé, mais ils ont préféré embaucher quelqu'un qui avait plus de bouteille.
The interview went well, but they chose to hire someone with more experience.
Ce jeune homme n'est plus l'adolescent insouciant que j'ai connu; il a pris de la bouteille.
This young man is no longer the carefree teenager I once knew; he has matured nicely.