A pending transaction is a transaction that has been authorised but has not yet been processed.
When a transaction is authorised, it is confirming to a business that your card is valid and there is enough money in your account to pay for what is being purchased.
A pending transaction reduces the amount of money in your account that you can spend (your available balance).
Pending transactions usually take up to 10 business days to fully process. After that time, either the business will claim the funds or they will be released back to your account.
If you let a business use your card for pre-authorised payments (like a security deposit for a hotel booking or car hire), you may need to wait up to a month for your payment to be returned to you.