This is a very old Islay single malt whisky from Bunnahabhain, distilled in 1980 and released at 45 years of age. As a single-cask bottling, it represents one individual cask rather than a larger batch, so its character is likely to be distinctive.
Bunnahabhain is widely known for a house style that is often less smoky than many other Islay whiskies, with an emphasis on malt, fruit, coastal character, and oak. Long maturation in refill wood can allow the distillery character and mature complexity to stay in focus rather than being dominated by fresh cask influence.