If you have clicked on Manually Enter Stock Financial Data, then the Symbol tab will be disabled. Otherwise, you will see a grid with the following fields:

• Symbol: The stock ticker symbol for a particular stock. To look up a particular symbol for a publicly-traded company, try https://finance.yahoo.com/lookup/. 
• Description: The description is directly linked to a Symbol and is usually the name of the public-traded company.
• Last Trade: The value of the last trade which is not a live value.
• Trade Time: The date-time stamp of the last trade value.
• Comments: For more information, you may click on the link to this stock.

By the way, the data in this grid is for personal use only.