The character is wearing school uniform. Most probably he/she's a student.
The standard school uniform or "seifuku" is a form of apparel that can be seen in much anime (more commonly, those that feature characters whom go to a high school) and is a very well known symbol to many otaku.
The school uniform is normally unique to a certain school, hence there is a large variety of uniforms that debut in anime, giving the artist flexibility with their work since they can design it based on what they want to see, and in most cases both a winter and summer uniform is featured which offers even more flexibility by using two separate colour schemes, widening the amount of people that it may appeal to.