When you create a campaign, there is a space for a description, but I can't see how a user would see this when choosing a particular campaign to support? Can you please advise is there is a way.
If you want users to view campaign description, maybe you can create a menu item to link to Campaign List view of Joom Donation. By doing that , when users click on the menu item, he will see list of campaigns (goal, description......), click on Donate Button next to each campaign to process donation for that campaign.