A phasor~ object, like other MSP objects such as cycle~ that use a rate for their timing, can have its repetition rate specified as a transport-related tempo-relative time value (note values, ticks, etc.). So if you want a phasor~ to work at a rate that is related to the transport's tempo, you can type in a tempo-relative time as an argument to specify its period of repetition instead of typing in a frequency.
The timepoint object sends out a bang when the transport reaches a specified time position. This can be useful for causing something to happen—or for starting an entire process—at a particular instant during the transport's progress. A timepoint might, for example, even trigger a new time position value to be sent to the transport object itself, thus causing the transport to leap to a different time.
This example shows one way you might use phasor~ to make the length of an audio sample loop stay precisely synchronized with the beat of the transport.
The translate object converts a message from one type of time unit to another. It uses the tempo and the time signature of the transport to do that calculation. If the tempo or the time signature changes, the result of the calculation would be different, so translate always resends its output whenever the transport receives a change to one of those values.