Visa means an endorsement in a passport or other travel document by an Immigration Officer or any official of Government so authorized, indicating that the bearer has been granted permission to enter or re-enter Malawi. ( See types and classifications of visas)
The visa gives permission to enter Malawi and apply for a visitors permit. If one has a valid visa, the department will not normally refuse anyone entry into Malawi unless your circumstances have changed, or you gave false information or did not disclose important facts when you applied for your visa.
When you arrive in Malawi, you should present all relevant documents to an Immigration Officer. This may include a printed version of your return flight itinerary or evidence of funds e.t.c.