FlowJo is a software platform used for data analysis in flow cytometry. It allows users to analyze and visualize their data with various color schemes. The '10 color combinations' in FlowJo refer to different palettes that users can apply to their data to differentiate populations or parameters. Common combinations include the default 10-color scheme and others like the 7-color or 14-color schemes. Each color represents a different parameter or population in the data.