Hmm, this can mean a few of things...
If someone were to ask me how my patient was tolerating the vent, the first thing I would think of is their ABG. The ventilator is meant to assist with oxygenation of cells, removal of CO2, and maintain a normal pH balance. The ABG is how we know whether the ventilator settings are sufficient for their patient's needs. Someone with more severe respiratory failure may require higher concentrations of oxygen- low arterial blood oxygen levels will indicate this may be the case. A person who is not initiating their own breaths very often may need a higher rate- high levels of arterial blood CO2 may indicate this.
The question may also address their sedation level. Are they sedated enough that they are calmly accepting mechanical ventilation? Are they fighting the tube and attempting to self-extubate? Are they so sedated that they aren't responding at all?
I would address both of those areas in your response to your instructor.