Data literacy has become an important part of STEM literacy and informed citizenship in our society. However, data literacy initiatives in secondary schools predominantly focus on narrow issues of developing students' ability to work with quantitative data and fail to address students' broader understanding both as producers and consumers of data. This study examined how secondary school students (N = 27) understand data and its relevance in everyday life. Students responded to a short pre-project survey and worked on a biology inquiry project producing poster-based science news. We inductively coded text responses and created themes that represent students' descriptions of data. We also analysed the nature of data students used while working on their project and producing posters. Results showed that students' understanding of data were limited to contexts of (a) experiment and survey, (b) utility and usage information, and (c) numerical charts and graphs. However, students used broad range of data in their authentic projects compared to their written description. Results provide insight about designing data literacy interventions and the importance of developing students' broader awareness related to the nature of data in everyday life.