There are two main approaches to validate data based on text containing specific characters (e.g., no symbols) in Excel:

1. Using the FIND function and ISNUMBER function:

This method checks if a specific character (or group of characters) exists within the entered text.

Here's the formula:

`=ISNUMBER(FIND("!@#$%^&*()_+=-`{[]};:'\",A1))`

* Replace "A1" with the cell reference where you want to validate the data.
* The characters within the quotation marks represent the symbols you want to disallow. You can add or remove characters based on your needs.

Explanation:

* `FIND` searches for the first occurrence of the specified characters within the text in cell A1.
* If a symbol is found, `FIND` returns a number representing its position in the text.
* `ISNUMBER` checks if the result of `FIND` is a number (indicating a symbol was found).
* The entire formula returns `TRUE` if no symbols are found (validation successful) and `FALSE` if a symbol is found (validation fails).

2. Using a Regular Expression with Custom Data Validation:

This method offers more flexibility by using regular expressions to define the allowed characters.

Here's how to set it up:

1. Go to the "Data" tab and click "Data Validation."
2. Select the cell(s) where you want to validate the data.
3. In the "Settings" tab, choose "Custom" under "Allow."
4. In the "Formula" box, enter the following formula:

`=REGEXMATCH(A1, "^[a-zA-Z0-9\s]+$")`

* Replace "A1" with the cell reference for validation.
* The regular expression `^[a-zA-Z0-9\s]+$` allows only letters (uppercase and lowercase), numbers, and spaces. You can modify the expression based on your specific needs (e.g., allowing commas or hyphens).

Benefits of Each Method:

* Method 1 (FIND & ISNUMBER): Simpler to set up, good for basic validation of specific symbols.
* Method 2 (Regular Expressions): More powerful and flexible, allows for complex character restrictions.

Additional Tips:

* You can customize the error message displayed when invalid data is entered in the "Error Alert" tab of the Data Validation window.
* Remember to adjust the cell references and regular expressions based on your specific needs and the characters you want to allow or disallow.