There are a number of reasons why the Netherlands rebelled against Spain back in the 16th and 17th centuries.
The Hapsburg Empire, run by Spain, was iunvolved in a large number of wars all over Europe, especially. A lot of the countries they were fighting traded with the Netherlands. The Netherlands also had to help pay for these wars. They did not like the wars because they had to pay for them and because the war hurt their trade.
Second, the Spanish were Catholic while the people of the Netherlands were Protestant. This was a big deal at the time.
Finally, the Hapsburgs were trying to take more power for themselves and leave less power to the people of the various regions (like the Netherlands) that they controlled.