One penny coins of this type are issued by the Royal Mint as "non-circulating legal tender" (NCLT) - i.e. for collectors, and are not intended for circulation.
This coin was issued to celebrate the birth of Archie Harrison Mountbatten-Windsor, the first child of Their Royal Highnesses The Duke and Duchess of Sussex (Prince Harry and Meghan).
The Royal Mint says:
"Join The Royal Mint in welcoming The Duke and Duchess of Sussex’s first child. To help continue the age-old tradition of crossing a baby's palm with silver, The Royal Mint has produced these charming sterling silver UK pennies.
The Duke and Duchess of Sussex’s relationship has captivated the imaginations of people from all walks of life across the world. No doubt millions of fans across the globe will be wishing the new baby a happy and healthy life - one guided by the spirits of service and warmth exemplified by its mother and father.
Finished to Brilliant Uncirculated standard, this sterling silver UK penny is the perfect way to capture such a joyful occasion."