Modernismo is Spanish for Modernism, however with the term Modernismo generally some more specific art movement(s) are intended:
Modernismo as term in architecture generally refers to the (pre-) Art Nouveau style existing e.g. in Barcelona in the last decades of the 19th century, the time Antoni Gaudí finished school and built his first projects.
But modernismo might also refer to a broader artistic movement, e.g. in Spanish-language literature.