There are two motions to postpone, Postpone Indefinitely and Postpone Definitely. They have very different uses.
Postpone Indefinitely is a motion used to kill a motion without actually voting on it. If a motion is Postponed Indefinitely, It cannot be brought up again in the same session, except by the motion to reconsider. The motion to Postpone Indefinitely requires a second and a majority vote and it is not debatable. If the motion is made and seconded, the chair puts it immediately to vote.
Postpone Definitely allows a motion to be postponed until a specific time or when a specific condition has been met. So you can postpone until the next meeting, or a specific time in this or the next meeting, or until a certain person arrives, or specific information is obtained Etc. This motion requires a second and a majority vote and is amendable as the time or condition to be met. There is a time limit on the postponement. Normally, postponement cannot be longer than until the next meeting, if that meeting will take place within 3 months. If the interval between meetings is longer than 3 months, postponement is not allowed.