This 2015 £1 coin is no longer in circulation, all round £1 coins were replaced in 2016/2017 by the new 12-sided Nations of the Crown £1 coin.
The coin design by Timothy Noad shows a depiction of the Royal Arms. The edge inscription reads DECUS ET TUTAMEN. It was the only circulation £1 coin to feature the fifth portrait of Queen Elizabeth II.
Circulation mintage: 129,616,985 coins, since demonitisation on 15th October 2017 - it is likely that many of these have now been melted down to create new coins.
Like all round pounds, the 2015 Royal Arms £1 is no longer legal tender, but can still be paid into most banks at face value.