Layer-2 is adding a top story to the blockchain to solve its issues.
Layer 2 refers to a secondary framework or protocol that is built on top of an existing blockchain base layer. The main goal of these protocols is to solve the transaction speed and scaling difficulties that are being faced by the major cryptocurrency networks.(Binance.(n.d))
Layer-1 is the term that’s used to describe the underlying main blockchain base architecture. On the other hand, layer-2 is an overlaying network that lies on top of the underlying blockchain. Consider Bitcoin and Lightning Network., Bitcoin is layer-1 network, while the lightning network is layer-2.(TheCapital.(2020))