What is blockchain on Iphone?

Excuse me, could you please explain what exactly is blockchain technology on an iPhone? I've heard about blockchain in the context of cryptocurrency, but I'm not entirely clear on how it applies to a smartphone like the iPhone. Is it a specific app or a feature built into the device? And what kind of benefits or advantages does it offer to users who have access to it on their iPhones? I'm really curious to learn more about this and how it can potentially impact the way we use our phones for financial transactions and other purposes.