The term "interoperable blockchain" belongs to the categories of blockchain, digital transformation and finance. A blockchain is like a digital cash book that many users keep together and that stores all transactions in a tamper-proof manner. In the early days, blockchains could usually only work individually. An "interoperable blockchain" makes it possible for different blockchains to communicate with each other and exchange data or values.
Imagine if blockchains were like languages: One speaks only English, the other only German. Without a common translation, they don't understand each other. Interoperable blockchains act like a translator. For example, they help you to transfer digital coins or information from one blockchain to another without having to go through the hassle of exchanging them first.
An illustrative example: Peter owns bitcoins that are stored on the Bitcoin blockchain, but wants to move them to a programme that runs on the Ethereum blockchain. Thanks to an interoperable blockchain, Peter can easily move his bitcoins to the desired programme without first having to sell his bitcoins and buy new digital currencies.
Interoperable blockchains are therefore an important step towards better connecting digital worlds and making them more flexible.