Many entrepreneurs today work for at least part of their work with international partners, suppliers or customers. This is mainly in English; so it is not surprising that most Dutch entrepreneurs think that their English is fine.
Internet broadens the playing field. That means more opportunities, but also more competition. The move abroad has been made easy thanks to platforms such as Amazon and advertising services such as Facebook and Google. But language is only one barrier, there can be many more. Such as culture (yes shaking in Bulgaria for example), way of buying (paying everything with cash in Germany), way of buying online (in the same Germany 54% of all e-commerce goes via Amazon), and of course the marketing itself. Here you can read articles about doing business internationally.