Vacuum pressure describes pressure below a stated reference, usually the surrounding atmospheric pressure. The reference and units are needed to interpret a reading.
What this means at your property
Extraction or drying equipment may use a pressure difference to move air or liquid. A pressure specification alone does not establish performance at a material surface because hoses, seals and the setup also matter.
What should an equipment explanation include?
Ask what is being measured, where the measurement applies and how the setup suits the proposed task. Keep equipment specifications separate from the observations and moisture readings used to evaluate results at the property.