Maxis

The term “Berlin umbrella” seems to primarily refer to a few different types of physical umbrellas or products associated with Berlin-based companies:
* Garden/Patio Umbrellas (Berlin Gardens): Several search results point to outdoor umbrellas made by a company called “Berlin Gardens.” These are large umbrellas for providing shade on patios and decks.
* Small, Collapsible Pocket Umbrellas (Knirps/Hans Haupt): Historically, the first telescoping pocket umbrella was invented in the 1920s by Hans Haupt in Berlin. He called it a Knirps (“little guy”), which became the generic German term for a small folding umbrella. This is a significant point in the history of the accessory.
* Merchandise/Branded Umbrellas: You can find umbrellas branded with “Neumann.Berlin” (a company in the audio industry), “BG Berlin” (a travel gear company), or the “Berlin Thunder” sports team.
Given the image you provided is of a person wearing a long, floral dress, and you are asking about “Berlin umbrella,” it is highly unlikely to be a style of dress.
If you were wondering about the umbrella itself as a fashion accessory, the term is more related to its historical invention as a compact, portable item for rain protection, popularized from Berlin.