There is no such thing as an absolutely accurate or a perfect measurement. A measurement's accuracy represents how closely it represents the actual value. Instruments themselves obey physical laws and usually interact with the phenomenon being measured, limiting measurement accuracy. Tables of these accuracies are usually published in operating manuals.
Resolution is the smallest measurable change that can be detected.
The DMM has a resolution of one least significant digit. The resolution of the scope and function generator depends on how good your eyesight is. Precision specifies an instrument's ability to repeat a given measurement. If you measure a resistance using the ohmmeter mode on the DMM and then come back a few minutes later, you should record the same value for the resistance. However, instruments can drift and the stability of the measured phenomenon may be in question.