A list is a collection of phone numbers that have subscribed. You can create lists to categorize your subscribers. For example, you might have a list named "FREE PIZZA". All the people that message in to that list will be added to the "FREE PIZZA" list. You can then send messages to people of that list.
Bananas are our version of credits. 1 SMS message sent or received costs 1 banana. 1 MMS(picture) message costs 3 bananas. A phone call costs 2 bananas.
Numbers are phone numbers. You will be assigned your own phone numbers that subscribers can send messages to.