When you have a PlayStation gift card worth 20 and are looking to sell it, there are several options available.

Online marketplaces can be a good choice. There are platforms where individuals can list their gift cards for sale. You can create a detailed listing including the value of the card, its expiration date if applicable, and any other relevant details. Potential buyers can then browse through these listings and make offers if they are interested in purchasing the PlayStation gift card.
Another avenue is to consider local classified ads. You can post an ad in your local newspaper's classified section or on community notice boards. This way, people in your area who might be interested in buying the gift card can easily see your listing. It also gives you the opportunity to interact directly with potential buyers and negotiate in person if needed.
You could also explore selling to gaming enthusiasts in local gaming groups or forums. These communities often have members who are constantly on the lookout for gaming-related items, including gift cards. By posting in these groups, you can target a specific audience that is more likely to be interested in purchasing your PlayStation gift card.