Belgium.
Brussels is a city, not a country, and it is not bordered by any country other than it's own - Belgium. If you meant, "What country borders Belgium?", the answer is: Netherlands, Germany, Luxembourg and France.
Belgium is a country in Northwestern Europe.
Amsterdam is not a country, but a city in the Kingdom of the Netherlands. The Netherlands is bordered by Germany, Belgium, and Luxembourg
Germany borders the Netherlands, Belgium, Luxembourg and France.
Belgium is the country you are looking for. The Netherlands is bordered by Belgium, Germany and the North Sea.
The Netherlands is a country. It is not in any other country.
Luxembourg.
there are several, Lichtenstein, Belgium, Luxembourg and the Netherlands.
France, Germany, The Netherlands and Luxembourg all border Belgium.
Luxembourg is shown on the map at the related link below.
Luxembourg and Belgium are both bordered by France and Germany