There are a lot of ways to translate your WordPress site.
You can use an automatic translation widget such as Google Translate. You can use a fully-featured plugin such as WPML. You can use a professional translation service such as Acclaro.
However, I don’t think I’ve ever seen a translation service as slick as Weglot.
Weglot is a WordPress plugin that connects to a SaaS service. It will translate your site automatically and then allow you to fix any mistakes in the text.