setting up specific amount of characters

I have an excel file that when I copy and paste data one of the colums has way too much information. What I want to do is see if there is a way to limit the column to lets say the first 25 characters.
EX)
Lets say column D contained the following
abcdefghijklmnopqrstuvwyyz
So there are 26 characters is there a way to limit that to lets say the first 13
abcdefghijklm
Is there a simple formula or setting I can change?
Thanks

Formula approach: =Left(A1,25) will give the first 25 characters, or the whole string if it has fewer characters.
For entering new data, you can use Data Validation, Text Length, set Min to 0 and Max to 25.