Help me interpret it (related to skilled immigrants in Canada)

When your application needs to be submitted to a visa office, ask the visa office what information you need to submit. If you don't intend to submit the complete application materials within 120, don't submit the application now. The visa office strictly limits the time of 120 and will not extend it.

Once the time limit of 120 days is exceeded, the visa will be refused if the materials are incomplete.

Application materials should be sent by parcel post.

When the visa office receives your complete application, it will send you a notice telling you what to do next.