A pending transaction is where you've paid using your card is expected to leave but hasn't yet.
It happens when the merchant's banking provider doesn't take your money straight away once you've bought something.
If you see a pending transaction in your recent transactions online or via the app. The money used in a pending transaction isn't available in your balance.
The transaction clears when the merchant takes it from your account, this is often quick but can take longer, up to 7 days. Once it clears your balance will change.
If for some reason the merchant never takes your money it will be returned to your account.