To add to what Jim posted: the choices JMP presents to you when you right-click depend on the data you've selected. For example:
If you've selected the first few terms in an arithmetic or geometric sequence, JMP will offer to continue (or, alternatively, repeat) the sequence.
If you've selected a range of cells where there are "gaps" of missing values, JMP will present an option to replace the missing values with previously encountered values.
Cheers,
Brady