Here it is Holanda, so I thought Holland and The Netherlands were the same thing... anyway, sorry.
Like Playmofire said, "Holland" is a province in The Netherlands. But we belgians too sometimes generalize and call all the Dutch (people living in the Netherlands) often "the Hollanders" ... especially when our national soccer-teams play against each other
"Low Countries" also applies or used to apply to Belgium, well Flanders in the north at least.
Until ca. 1585 - when the Spanish troops of King Philps II split us up - we and our nothern dutch neighbours formed 1 country. The Netherlands as it is now known, comprised "the Nothern Provinces" and Flanders "the Southern Provinces".
The South (Flanders) remained under Spanish occupation for a very long time and so there is much catholic influence in our culture. The North (The Netherlands) succeeded in holding off the Spanish troops and they are mostly Protestant.
There was a short reunion in the 19th century, but we revolted against the North and became independent. That led to the creation of Belgium.
We still speak the same language which is Dutch, though in Flanders (nothern part of Belgium) it is with a different accent and so the language is called Flemish.
The reason Saint-Nicolas is allways depicted with black (African) assistants, is because according to the story he came from Spain. And in medieval times, many parts of (southern) Spain were often invaded/occupied by North-African Saracen troops, who were called "the Moors" and the populations got mixed up somewhat in certain regions in Spain.
Btw, I think the word "morion" - like used for the typical soldiers' helmet - is related with that. "Moor" was also used in dutch/flemish language and is an old word for 'black', probably we got the use of that word...again thanks to the Spanish occupation in the 16th C.
Black cats still often get the name "Moor" or "Moorke" here.