Claudia,
You mark the item you're listing with the quantity you have. Assuming you tell it that you have 1 of the item, you mark that items to "not" sell once the quantity is exhausted. Then the listing remains with the words sold out. If you mark it to continue selling, then yes it will still be available to sell.
Hope that answers your question.
P.S. Once you decide on getting a shop there, let me know via contact and then you'll be able to join or FB group and get all the help you want.