You’ll deploy a simple Tezos smart contract written in ReasonML, using tezos-environment-manager. You’ll call the smart contract using sotez to verify the deployment. All of this will happen in a local, private and sandboxed Tezos blockchain.
Tezos is a blockchain technology, or in other words — a platform that allows you to build decentralised applications by implementing a blockchain ledger and smart contract support. You can learn more here.