Not sure how many physicists troll around craigslist, but if they do…
Hands down, the best description on a craigslist item EVER
FWIW, An oscilloscope measures two things: voltage and time. A charged beam of electrons “sweeps” the screen in a given time in the x-axis, and is deflected by a signal in the y-axis. The deflection from the standard signal in the trace can gauge the input signal’s voltage and duration/frequency.
And yes, the poster was correct. O-scopes are great.