Unfortunately, data validation itself cannot be directly dependent on the value of another cell in Excel. However, there are a couple of workarounds you can achieve to achieve a similar outcome:

Method 1: Nested IF Formula in Data Validation

1. Choose the cell(s) for validation: Select the cell(s) where you want to restrict data entry based on another cell's value.
2. Open Data Validation: Go to the "Data" tab and click "Data Validation" in the "Data Tools" group.
3. Set Allow and Formula:
- Under "Allow," choose "Formula" from the dropdown menu.
- In the "Formula" box, enter a formula using nested IF statements. Here's an example:

```excel
=IF($A$1="Yes",A1="",TRUE) // Replace $A$1 with the reference of your validation cell
```

This formula checks the value in cell A1 (replace with your actual cell reference). If it's "Yes", it allows any input in the current cell ("" means no restriction). Otherwise (if A1 is not "Yes"), it returns TRUE, which essentially restricts any input in the current cell.

4. Error Alert (Optional): You can set up an informative error message in the "Error Alert" tab to guide users on the valid input based on the other cell's value.
5. Click OK: Save your data validation settings.

Method 2: VBA Code for Dynamic Validation

This method requires using VBA (Visual Basic for Applications) code. It offers more flexibility but involves writing code.

1. Open VBA Editor: Press Alt+F11 to open the VBA editor.
2. Insert Module: Insert a new module by right-clicking on your project name (VBAProject) in the Project Explorer pane and selecting "Insert" -> "Module."
3. Write VBA Code: Paste the following code into the module, replacing `Target.Offset(0, 1)` with the appropriate cell offset to reference the validation cell:

```vba
Sub ValidateCellBasedOnAnother(ByVal Target As Range)
Dim validationCell As Range
Set validationCell = Target.Offset(0, 1) // Adjust offset as needed

If validationCell.Value = "Yes" Then
Target.Validation.Delete ' Remove any existing validation
Else
' Set your validation rule here (e.g., data type, list, etc.)
Target.Validation.Add Type:=xlValidateList, Formula1:="=DropdownList" ' Replace with your specific validation rule
End If
End Sub
```

4. Assign Macro to Worksheet Events: Go back to your worksheet. In the "Developer" tab (if not visible, you might need to enable it in Excel settings), click "Insert" and choose "Module." Assign the "ValidateCellBasedOnAnother" macro to the "Worksheet_Change" event. This will trigger the code whenever a cell value changes, dynamically updating the validation based on the other cell's value.

Choose the method that best suits your needs. The formula approach is simpler but limited, while VBA offers more control but requires coding knowledge.