Ganache is a tool to set up your own local Ethereum blockchain that you can use to deploy and test your [dido:public:ra:xapend:xapend.a_glossary:s:smart_contract]] / Distributed Application (ĐApp or DApp) before launching them on an authentic chain. As such, Ganache enables developers to avoid paying unnecessary gas fees during the developing process.
Source: https://moralis.io/truffle-explained-what-is-the-truffle-suite/