Yes you can! A reserve price is the lowest price at which you are willing to sell your item through an auction listing. If you don’t want to sell your item below a certain price, you can a set a reserve price. The amount of your reserve price is not disclosed to your bidders, but they will see that your auction-style listing has a reserve price and whether or not the reserve has been met. If a bidder does not meet that price, you're not obligated to sell your item.
Many sellers have found that too high a starting price discourages interest in their item, while an attractively low starting price makes them vulnerable to selling at an unsatisfactorily low price. A reserve price helps with this.