It varies. Viral pneumonia (majority of pneumonias) do not treatment with antibiotics and resolve on their own in 7-10days. This is provided you are not immunocompromised.
Bacterial pneumonia need antibiotics and usually resolve in 7-10days with treatment.

Most pneumonias resolve in less than 2 weeks with antibiotics. If there was an abnormal chest x ray, that may take longer to return to normal even though you may no longer have symptoms

Practice deep breathing and don't suppress the cough, and you will get better quicker.