What is bitvm (bitcoin virtual machine)?

Could you elaborate on the concept of bitvm, or Bitcoin Virtual Machine? I've heard it mentioned in the cryptocurrency community but am unclear on its exact role and function. Is it a platform for executing smart contracts on the Bitcoin blockchain? How does it differ from Ethereum's Virtual Machine? Also, what are the key features and advantages of using bitvm? I'm interested in understanding its potential implications for the development of decentralized applications and financial services on the Bitcoin network.