I am a noob when it comes to CLI. I am trying to use my Optimism Safe using CLI but I don't know what "Ethereum Node URL" is in this command line: safe-cli <checksummed_safe_address> <ethereum_node_url> Can you help me, please?
An Ethereum node URL referes to the endpoint of an ethereum node you want to connect to - the nodes are basically software that connects to the Ethereum network and allows you to interact with it.
<ethereum_node_url> will connect you to a node, it is basically your gateway to the Ethereum network so you can interact with the blockchain.
Examples of Ethereum node URLs could be on your local machine or a public node provided by a blockchain service like Infura or Alchemy. You need to sign up to get your URL with API key and then get the URL for the network you want to connect to (Optimism as it seems in your case).