Dutch law offers a high degree of protection for employees. You can inform yourself of your rights and responsibilities by reading this recent brochure issued by the Dutch government for European labour migrants.
In case you need legal advice, you can approach the Groningen office of the Juridisch Loket (legal support office). They will offer you free legal advice on many topics. The website is in Dutch but support can be offered in English.
In case of discrimination, you can report it to the Discriminatie Meldpunt (discrimination contact point). Again, the website is in Dutch but support can be offered in English.
Elsewhere these topics related to work are covered :