Ema, thanks for reading! Those brackets come from EJS. Did you npm install EJS and require it at the top of your app? Also you may need to install a syntax plugin for vscode to recognize EJS syntax.
For the app listen, that is a function from express. And if you look at the documentation https://expressjs.com/en/api.html you will see that the function includes an optional callback: app.listen(path, [callback])
Is express also installed and required in your script?