Can I use abbreviations in common app activities section?

So I’m trying to describe one of my activities yet but am struggling to fit all of the info because of the short character count. Is it okay if I wrote “&” instead of “and” or is that unwise?

It is fine.

What I did in my Common App was I used some abbreviations in the activities due to word count, and then if it is a not-so-obvious abbreviation (especially if has your high school’s name or a specialized club) you can put the abbreviation in the Additional Info section where you can write it as
“Activities section:
[abbreviation] - [written out meaning].”

At least, that’s what I did for mine.

It’s fine to abbreviate words, but you don’t want it to read like a text message.