scilloscopes are commonly used to observe the exact wave shape of an electrical signal. In addition to the amplitude of the signal, an oscilloscope can show distortion, the time between two events (such as pulse width, period, or rise time) and relative timing of two related signals.
It's a Voltmeter that is able to show volts as a function of time. But yes it can be used for all of those functions. But it looks like his is only a single channel oscilloscope so you can only view a signal source at a time.
These are close ones I use in my classes pretty frequently. (Its just a model newer or so, same functionality)
Nice work for getting that oscilloscope for free, but I probably wouldn't spend money on one like that, as for a bit more you can getter a higher-quality with more functionality.
A nice thing about lab equipment tho, a scope from 20 years ago works almost as good as a brand new one from today, old ones just cant perform as many math functions, or print images to usb key.