It is a cue that is made in a factory-like production setting. Generally it means that the specs on the cue are pre-determined by the factory and only things like wrap, tip, color and weight can be changed at little to no extra cost.
Semi-production would denote a cue maker whose cues are all the same specs but that they will do more customizing than a production shop. Custom would mean that the cue maker would be willing to change just about anything you want within reason. Most small cue makers fall between semi-production and full custom.