This shows how much disk space you have left on the current drive and then tells you how much every file/directory takes up. e.g.,
Filesystem Size Used Avail Use% Mounted on
/dev/sdb2 206G 167G 29G 86% /
115M node_modules
2.1M examples
68K src
4.0K webpack.config.js
4.0K README.md
4.0K package.json
df -h .; du -sh -- * | sort -hr