Foreigners who would like to study at the universities of Netherlands in English need to show their knowledge of the English language by passing following exams:

• The TOEFL® Test (Test of English as a Foreign Language™).
• Academic IELTS test (the International English Language Testing System).
• A Cambridge Certificate in Advanced English (CAE), Proficiency of English (CPE) or First Certificate in English

Exceptions are allowed for students, who get second higher education in English, or for the students whose mother tongue is English. See the list of English native speaking countries. 

These English exams measure the ability to communicate in English for those who want to get education in Holland. Language admission requirements at Universities in the Netherlands

Language admission requirements at Universities in the Netherlands

Below you can find the list of necessary scores for admission on Preparatory, Bachelor and Master programmes at universities in the Netherlands.

Here you can see the several equivalency tables for TOEFL and IELTS scores.

Source: English Language Center

Read more:  Preparatory programmes, TOEFL and IELTS test.

This is another conversion table, where the levels proficiency in English are shown.

Source : Vancouver English Centre

Read more: Admission at Universities in Holland,  Language and preparatory programmes  and  TOEFL & IELTS test centers in the Netherlands