Answer:
There are various ways to approach this question, but I will assume that you mean you, as a native speaker of English, are listening to a person who has grown up with another language and learned English as a second language.
From my experience, people from the Netherlands and Denmark often speak English very clearly and fluently. It may be that, because their countries (and the number of speakers of Dutch and Danish) are relatively small, they early on recognize the limitation posed by NOT learning other languages. Those languages are also in the Germanic group (as is English), so there is more grammatic similarity between Dutch and English than there is between French and English. I also met Germans who spoke English extremely well, but other who did not. A German chould probably get by much better than a Dane speaking only his own language, because there is a larger area where German is the main language. Non-German speakers to visit Germany of course, but relative to the size of the country, many more non-Danish speakers visit Denmark.
Spaniards and Italians often learn French as their second language, and add English as a third one--beginning when they are older, so they may never reach the same level in English as they have in French.