What they meant by it is difficult to say. Technical phrases between Chinese and English don't translate very well either direction, especially by either automated or unskilled translation means, which is the majority of what can be found out there in documentation.
However, if it doesn't work in either mode, 0 or 1, it doesn't really matter for this specific problem.
The "imitation torque mode" could refer to either the way it drives the motor, or the way it is controlled via the pedals.
Motors can be controlled by speed control, which is the most common, or by torque control.
The former just outputs a voltage to the motor proportional to how much throttle (or assist level) is used, which causes the motor to spin at a particular speed.
The latter outputs a current to the motor proportional to the throttle/assist level usage, whcih causes the motor to provide a particular amount of torque. This is a more precise way of controlling motor power, and can give a lot smoother control. But it's not usually in cheaper controllers, though some have the "imitation" version that is a little better than the regular speed control. Whether yours supports that or not, I don't know.
To find out if this is what yours means, and if you have the support for it, you can set it to that and ride using throttle, and see if it "feels" different in one mode than the other, mostly for acceleration from a stop, or throttle changes in general. If there's no difference, either yours doesn't support it or it isn't the motor control it's referring to.
If it refers to pedals, there are two basic ways to use a PAS sensor. Cadence sensors like what you have just detect that you are pedalling or not and control the bike's speed based on whether you are pedalling or not plus the assist level you chose. They *could* be used to detect how fast (though most don't do this) you pedal and directly control the speed of the bike as if the pedal speed was a throttle; my SB Cruiser trike does this via the Cycle Analyst v3 (the controllers I use don't have PAS). It's possible that this latter mode is "imitation torque" mode for your controller.
The other basic way to use PAS is to have an actual torque sensor in the cranks (or human-power chainline somewhere) to detect how hard you are pedalling, and then the controller can provide assist power based on that. Yours doesn't have a torque sensor, just cadence, so it might do as I noted above and use the speed you pedal at to imitate this control mode.
Easy to tell if the PAS was working, because you'd be able to vary speed based on pedal speed, rather than having to change assist level to go faster (regardless of pedal speed).
The disadvantage of that way of doing this is that if you can't pedal fast enough to get full assist like on a steep hill, or when first starting out from a stop, you won't get enough assist to keep going or get going, either. That's when having an actual torque sensor is useful, because it can still tell you are really mashing down on the pedals and provide extra power to help you.
But it's more expensive and more complicated so it's not nearly as common as pure cadence sensors like yours.
