Approving an item will cause system events to trigger. These events may differ depending on what is approved. Overall the point of this is generally to automatical create and update data, and send emails based on what was approved.

Examples of automatic approval events:
Approving anything will typically do the following:

Raise an audit record.
Send an email to the submitter to notify them of the approval.
Update the submitted item status to 'Approved'.
On top of the above list, here are some of the events that trigger on particular item approvals:

Contract extension:

Update any dates listed on the contract record to respect the newly exercised extension.
Update any non-exercised extensions so that the dates represented on those are in line with the new contract dates.
Contract variation:

Update any dates or financial values listed on the contract record to respect the newly approved variation.
Create extensions (if listed as a component of the variation).
Update the schedule of rates for the contract (if schedule of rates exists, and variation impacts value of contract).
This ability to hook in automated events when approvals occur makes approvals in Nimblex both powerful and scaleable. The default approval events are kept quite generic as to not be overly complex to the point of making them confusing, however, through a change request these could be tailored to meet individual organisation needs.

Some examples of additional events that might make the solution fit more for you (note these are build-on-demand and some options may require additional integrations):

Automatically push approved document to TRIM.
Notify specific departments of approvals.
Schedule a calendar event.
Generate a PDF / Word document, e.g. a mail merge document auto-populated with information from the system.
Create a user and send system access.
Publish tender to procurement market place.
Trigger HTTP request - a potential solution for pushing information to remote systems (depends on capabilities of remote system).