Whenever someone applies for a leave, an email as well as a Notification is sent to the manager as well as the HR Manager. So you can simply approve/Reject by clicking on the Approve/Reject link you received in the email.
In case you have missed the email or you have not received it, just do the following
1. Login into uKnowva
2. Click on My Team's leave history in the Left Menu (In case you do not see that menu, then click on My Leave history and then click on Team's Leave History)
3. Click on the Approve / Reject button.