A pending transaction should take between a few minutes to a few hours to go through assuming you have the funds in your bank, on your card etc.
Some pending payments may take as long as 8 hours to 24 hours to process and come out of pending payment status.
If you're referring to something you bought on Ebay and paid for the item and the transaction is in pending status then just give it a few minutes or at least an hour and the pending payment should go through.
Some days when I buy something on Ebay the payment stays pending for a few minutes and then some days the payment stays pending for a few hours.
I know my bank account that is linked with Paypal has the funds in it so I just wait it out and then it processes.
I used to worry about it at first because one day it took a whole day before it processed but it was just the paypal and bank system causing the delay.