Although Combo network is an L2 (and therefore fundamentally connected to BNB Chain), it's also a separate blockchain system. App developers commonly need to move data and assets between Combo network and BNB Chain. We call the process of moving data and assets between the two networks "bridging".
For the most common usecase, moving tokens around, we've created the Standard Token Bridge. The Standard Token Bridge is a simple smart contract with the functionality you need to move tokens between Combo network and BNB Chain. It also allows you to easily create L2 representations of existing tokens on BNB Chain.
If the Standard Token Bridge doesn't fully cover your usecase, you can also send arbitrary data between L1 and L2. You can use this functionality to have a contract on BNB Chain trigger a contract function on Combo network and vice versa.