A:
There are two "division" motions: Division of the Question and Division of the Assembly.
Division of the Assembly may be demanded by a single member (without seconding or voting), and requires that a vote that was taken by voice to be retaken by standing.
(See RONR p. 277.)
Division of the Question requests that a complex but divisible motion be divided into two separate motions.
This motion requires a second and a majority vote.
(See RONR p. 269.)
An example of a motion that could be divided is, "that the club purchase a printer and a scanner for its computer."
This could be divided into two motions: one for the printer, and one for the scanner.
An example of a motion that could not be divided is, "that the club purchase a computer and a support contract for it."
If it were divided and the motion for the computer was not adopted, it would make no sense to vote on whether to purchase a support contract.