Visual Cues and Icons in Tableau Desktop

Tableau provides many visual cues to help you evaluate the type of data that’s displayed in the Data pane and the state of a data view.

Data Sources in the Data Pane

The following table explains each of the icons used to describe the type of data sources in the Data pane. Each icon in the table can be modified by one of two indicators. 

Fields in the Data Pane

The following table explains each of the icons displayed in the Data pane. Each icon in the table can be modified by one of four indicators.
Fields on Shelves
Fields placed on shelves use a combination of icons, colors, and text styles as visual cues. 

Fields on the Marks card

Fields placed on the Marks card use specific icons to describe how they appear in the view. See Mark Properties. 

Sheets in the Dashboards and Worksheets pane



Reference: Click Here