Error Message on the Screen

I am not really that good at understanding different messages that would just appear right on my screen.
Can you help me sort this out?
A data validation dialog box keeps on appearing, and a lot of fields would surprise me then.
How may I be able to stop this irritating dialog box from popping out on my screen?

Data Validation:
Show error alert after invalid data is entered
When user enters invalid data, show this error alert:
Style: Stop . Title: Too many characters.
Error message: The maximum number of characters for this field is 25 – please try again
Any suggestions to eliminate this?
Please help me with this.
