In a typical credit card transaction, a hold is placed on your account for the amount of your requested transaction before the money is actually withdrawn. This hold is removed once the money has been transferred out of your account.
In some situations, a hold placed on an account will remain even though a transaction was declined. This happens most often when the billing address or CVV (the short number printed on your card) was entered incorrectly.
While these holds can be inconvenient, they will fall off of your account automatically after 3-5 business days. If you require access to these funds before the 3-5 day window is over, you can usually contact your card issuer and request to have this hold removed.