There are two switches on the center console right next to handbrake lever. One is the AT hold switch. The other one has a picture of what looks to be the rear window & wiper, with wavy arrows like on the rear defrost button.

What does it do....?

I thought maybe a wiper de-icer, but can't see any evidence of this...

what year is it please

windshield washer warmer, your car has the cold weather package basically, i bet this is a 95-99 legacy, or newer, but some of the 90-94 legacy's had them as well which i believe was the alpine edition.

aha. it is a jdm '95.