If you have been authorized to approve expense claims in Bezala, you can see all expenses waiting for your approval in the web version's home view.
You can examine the expenses by clicking on them - the form will then open in the middle of the screen and the attachment is shown on the right (in the mobile version the form will fill the whole screen).
Disapprove the expense by clicking on the "disapprove" button. After this you can write a message to the user and explain why the expense wasn't approved. After this the user can re-edit the expense and send it back to your approval.