The Formula bar

Formulas allow you to compute a value in each record based on other cells in that same record.

Example: =A1+A2+A3, which finds the sum of the range of values from cell A1 to cell A3.

In the sheet on the top right-hand side, you will see the fx icon in Green color. When you click on the fx icon, you will notice a rectangular bar with a Pointed arrow and Chain icon. This bar is called the Formula bar.
The Formula bar helps you to see the formula inside the cells.

When you click the fx icon, it highlights the cells in Green color. 

There are two types of modes available in the Formula bar.

1. Trace precedent mode

2. Edit mode 

Trace precedent mode

When you click on the cell, you will see the formula inside the cell in Trace precedent mode, i.e., you cannot edit the formula. However, you can click on the formula to view cross-references.

Edit mode

When you click on the Chain icon (Black), you will notice the change in the color from Black to White. This indicates the Edit mode is enabled.

Now, you can edit the formula in the formula bar.

Each row contains a specific formula; any changes in the formula can be implemented horizontally to all the cells in the particular row. To edit the formula, select the Chain icon, modify the formula, and press Enter to save the formula. 

You will see the new formula is applied to all the cells in row 38 of the sheet.