Translation:We celebrate carnival in the southern part of the Netherlands.
In the US, "Carnival" is called "Mardi Gras", and it's usually celebrated in the state of Louisiana. A "carnival" is usually made up of traveling amusement rides, vendors, games and acts. This seems to be closer to the Dutch word "kermis". A "fair" is typically a gathering of people to display or trade produce and animals, and may or may not have a travelling carnival associated with it. Thus "fair" translates to the Dutch word "jaarmarkt".
Eindhoven grinds to a halt during Carnaval which is the big blow out before Lent but religion is not a big thing anymore down south but the merrymaking traditions remain. Yes loads of people young and old dress up and participate singing drinking dancing drinking for about a week. There is also a parade with floats and those people take it very seriously. It is a lot of fun.
It's really not the same thing. The Dutch idea of carnaval is basically dressing up like a moron and getting drunk. It is probably the only time of year when the northern half of the country hides in shame, to avoid running in to full grown men in giraffe costumes. If you're looking for anything exotic, the Rotterdam street carnaval is more like what they would call carnaval in Brazil (beats, butts and ❤❤❤❤❤❤❤). ;)
When you're talking about a broad geographical location it's always in. In the west. In the eastern US. You don't throw a carnival, you celebrate it ( if you're talking about a festival that occurs approximately forty-one days before Easter) or you have it ( if you're talking about a random festival with rides. CARNIVAL in the sense of the festival associated with Easter is never or almost never referred to with an article. Your sentence is grammatically ( the words are in proper order, etc ) sound but semantically wrong, the first reading makes no sense.