Berlioz uses league/climate package to manage output.
CLImate allows you to easily output colored text, special formatting, and more. It makes output to the terminal clearer and debugging a lot simpler.
The console is accessible from environment variable passed in argument of CommandInterface::run(Environment $env) method.
Output
Example to colorize output:
// ...
$env->console()->red('Red output');
$env->console()->output('Normal output');
For all capabilities of console, refers you to the official documentation.