Is it from "Sure Electronics"? It sure looks like it
At first I thought it looked like one of their frequency meters that read from 0 to 9999 (Hz).
You'll need to point me at some info on the web. The image you have given us doesn't contain enough info.
Is it one of
these?
If so,
this is the manual.
It looks like you need to set some switches inside and then apply a voltage of between 5 and 12 volts to the input to cause it to count up one count.
There's no real description of what the "isolated" vs "non-isolated" inputs actually mean, so it's difficult to tell you how to wire it up. They also warn against getting the polarity wrong, so I'd heed that.
My best guess is that you should set it for counter and non-isolated input. Then measure the resistance between the input ground and the -ve supply rail. If there is continuity there, then you can probably connect the +ve input to the battery +ve via a switch and a resistor (just in case -- make it 10k).
If all goes well you should be able to push the button and watch it count up. It will probably count up several counts each time you press and release the button -- if it does that then there's more work to do.
I offer no guarantee that these steps won't cause the smoke to come out...