The term "research data" broadly encompasses any information collected or created that you use to validate research findings. All research, at its core, uses data.
Data can take many forms. Traditionally, people think of data as things like measurements, observations, survey responses, and interview recordings. Data can take other forms, too - photographs and art, archival records and accompanying research notes, and even pieces of literature can be research data depending on your context. Data management is just as important for less conventional forms of data as it is for more traditional forms.