If I had to guess this is a generator style anemometer. Where the three pins are "+ generator", "− generator", and "earth ground". To find out which is which is probably a matter of trial and error spinning the cups while using a multimeter.
Displaying the data probably requires a data logger of sorts - whether you want something industry standard like what Campbell Scientific makes or a more DIY approach like Raspberry Pi or Arduino. That is unless you know of it's make and model and may perhaps give you a lead for displays made for it. As far as the connector goes, I'd personally just cut it off and tin the leads if you establish there are no displays for it. Will make wiring it up easier, but that's personal preference.
Hope this helps.
Cheers
