What are the order of the phase?

A phase sequence test is performed before running a motor if the direction is critical. In a deep well the pump, it can be several 100 feet from the motor and driven by dozens of rods threaded together. Iit can be a bit of a hassle to haul it all back up and thread it all back together.

You can do a dry run with the motor to make sure its the correct direction before

hooking up the coupling. You can label the wires before you pull them or bury them.

You can make a phase sequence meter with a light bulb a capacitor and a coil. Put it on a source known to be 123 and label your wires 123 if the bulb lights. There are some manufactured meters that have a light for 123 and 132, that way you can switch labels rather than wires. Also, on the nice ones you can put it on the motor and turn it it the direction you want it to turn and call the wires 123. But, since most motors have the wires already labeled its probably better to label the switch correctly.

Phase sequence is more important in a parallel operation of two sources of Electricity. The phase sequence has to be same before a successful parallel operation. It is not enough to check the sequence only on the motor direction. Use the meter or bulb method to ensure the right sequence.