Character Limits can be added to Single Text Line Questions on an eForm. This means that when someone is filling out a response to the question they will only be allowed to put characters based on the limitations you have set in the Minimum and Maximum boxes. If these boxes are empty, there will be no limits to the number of characters that can be in a response.
To do this:
Add a Single Text Line Question to your eForm
Adjust the Minimum and Maximum boxes to the limits you would like to set.