It is an interface for interacting with RPC Cosmos directly from your application. To begin, you need to connect to the Cosmos node via RPC. To do this, find a node to connect to or deploy your own on-site
https://getblock.io/nodes/atom/ The Cosmos documentation has everything you need to do this: from the configuration to the list of available RPC commands. If anything happens, you can always ask for advice in the Cosmos community - the guys there are responsive. Good luck with your projects!