Neerlandês vs. holandês
The Portuguese words neerlandês and holandês both refer to the Dutch language and people, but they have slightly different connotations and usage.
Neerlandês
B2Neerlandês is the more formal and technically correct term for the Dutch language and people from the Netherlands.
Ele está estudando neerlandês na universidade.
(He is studying Dutch at the university.)
A literatura neerlandesa é rica e diversificada.
(Dutch literature is rich and diverse.)
Holandês
A2Holandês is the more commonly used term in everyday language, often used interchangeably with neerlandês, but technically refers specifically to things from Holland, a region of the Netherlands.
Meu vizinho é holandês.
(My neighbor is Dutch.)
Queijo holandês é famoso mundialmente.
(Dutch cheese is world-famous.)
Summary
While neerlandês is the more precise term for Dutch language and people from the Netherlands, holandês is more commonly used in everyday Portuguese. Both are generally acceptable, but neerlandês is preferred in formal or academic contexts.