Watch Window in Excel

Adding a Watch Window

Select the cells you want to watch. On the Formula tab, in the Formula Auditing group, click on Watch Window.

Click Add Watch.

Click Add.

Note: You can move the Watch Window toolbar to the top, bottom, right or left side.

To display the cell that an entry in Watch Window toolbar refer to, double click the entry.

Removing cells from the Watch Window

Select cell that you like to remove. To select multiple cell, press CTRL and then click the cells.

Click Delete Watch.

Further reading: 
Formula auditing
How to count cells with a specific content in a range?
Dynamic chart title from the cell