Credits are a virtual currency made available to professional clients. They can be part of your contract or purchased online and have a duration of 6 months.
The options that can be purchased with credits are
“Featured Listing” which allows placing a Listing at the top of the list above all others to make it more visible. The "Featured Listing" option is available for both Professional and Non-Professional Listers.“Highlight” which allows highlighting a Listing in a coloured box to make it more attractive.
“Flash Sale” which allows applying a discount to the selling price of a property for a limited period to speed up the sale of the offered property.
“Available for Rent”: which allows adding the mention "available for rent" to a Listing for sale.
If you are a "Non-Professional advertiser" (referring to any individual or legal entity who has an Account, and whose main activity is not the sale or rental of goods), you cannot use credits
Please refer to the article on visibility options.