Where can someone approve a transaction that requires an e-signature?

If users initiating a transaction are also approvers for the transaction, they see the Initiator Approval section on the E-Signature page where they can approve e-signatures.

If other users in the task flow must approve the transaction first, this section appears only when a user becomes eligible to approve the transaction in accordance with the task flow. Other approvers can approve the transactions through the notifications in the BPM worklist page or from the notifications on the home page of their application.