Can you tell me how I can have my site in two languages?
You can use WPML plugin to make your site in multi language.
But that plugin is not free, do you know if there is a free one? These plugins integrate fine with Tractor theme, can I use the already existing controllers on my website? (see the attached image)
Attached files: Screenshot 2019-08-19 at 18.14.33.png
That language switcher is just the demo menu. It can not be work. The WPML plugins is compatible with theme. With other plugin, we can not be sure if it can work. You can try to use G-translate plugin to make your site in multi language.