Firstly, install node on your machine. you can download the latest node js (https://nodejs.org/en/download/) and install it.
Please confirm node and npm installation using below commands
Now, you can install react native by using following command in terminal :
npm install -g react-native-cli
We can run react native app in an emulator to test it. For this we have to setup ANDROID_HOME environment variable ( Computer → Advanced System Settings → Environment variables → New, then enter the path to your Android SDK ).
Create your first project using below command from the folder where you want to create the app.
react-native init demoReactApp
run the command to start package, make sure you started the emulator.
The demo project will be open in the emulator.