Your layer uses data in a SQL Server database. This is not supported when publishing to ArcGIS Server (Linux), as ArcGIS Server (Linux) cannot connect to a SQL Server database.
Solution
Either move your source data to a database or geodatabase to which ArcGIS Server (Linux) can connect, or publish to ArcGIS Server (Windows).
If you move your data to a different database, reset the data source path for your layer in the map. Do this by using the Set Data Source button on the Source tab on the Layer Properties dialog box. To change the data source used by multiple layers in an ArcMap document at once, use the Set Data Source command in ArcCatalog. Access this command by browsing to the folder in ArcCatalog where your map document is located and right-clicking the map document.