Mañana means tomorrow in Spanish, and mañana mañana is procrastination at it's finest.
Mañana mañana implies that you are putting it off for another day, but it may, or may not get done that day, or even attempted.
It is usually tomorrow as in "Hasta manana" (see you tomorrow). However there are alternative uses, such as in "por la mañana " (in the morning (no specific time)).