Visa, Schengen

The schengen visa ia a visitor's visa which can be used in all of the 15 or more countries who are covered by the Schengen Treaty. So if you are travelling to Spain but want to visit Holland first, since both of these countries are schengen countries you can apply for a visa to be issued for your long stay in Spain (extensions are difficult to get so apply for the longest period you want which can be approved) and use the same visa to first visit Holland before proceeding to Spain.