How to use more than 80 characters in page layout section Name in sales force
I can see a few options to this, as per our discussion in the comments. Given your goal to add a description aspect to your section.
NOTE: That neither of these options, will sadly appear in Edit mode.
Finally, though not directly related to your question, but in relation to make the native UI more descriptive, don't forget you can also provide field level descriptions, which surface as little yellow popups when the user hovers over the question mark icon.