Holland is the name of a region in the western part of the Netherlands. Holland was a county of the Holy Roman Empire and later the leading province of the Republic of the Seven United Netherlands (1581–1795).
Today, there is no country called "Holland". There are two provinces called "Holland" in the Netherlands: North Holland (Dutch: Noord-Holland) and South Holland (Dutch: Zuid-Holland). Those provinces were created in 1840. The earlier country and province of Holland used to be bigger, but some parts of that province were given to other provinces during the French occupation (1795-1813). For example, Willemstad became part of North Brabant, the islands of Vlieland and Terschelling were given to Friesland, and the island of Urk to Overijssel. But for a short time during that period (1806–1810), there was a country called "Holland", the Kingdom of Holland, which was in the central and northern Netherlands and East Friesland in Germany.
Many people use the name "Holland" to refer to all of the Netherlands, including the other ten provinces. That is not correct and is like calling the United Kingdom, "England" or "Great Britain". Some Dutch people who live outside "Holland" find it unacceptable to refer to the entire country Holland. But acceptable when you refer "Holland" to the Netherlands national team.