The "Elto" is a transformer arc welder ( known as a "buzz box" in USA ). There is nothing in the box apart from a transformer with a heavy-current secondary winding and a movable iron core. Yes, you can check if it works by measuring the open-circuit secondary output voltage ( the OCV ) with a meter set to AC volts. It will be about 45 to 75 volts AC. It probably does work, there's almost nothing to go wrong.
The sliding control knob on the front panel moves part of the transformer iron core. The position, and the corresponding arc current, is indicated by the pointer on the top panel. Moving the core will change the current, the OCV remains fixed.
At that price, if it works, it would be an OK way to start learning arc welding. A modern inverter arc welder, which provides a DC output for a smoother arc, and has features such as anti-stick, would be easier to use - but will cost 5 to 10 times more.