This is the 5th book but just a collection of short stories from the world of Earthsea. There is only one short story in here that connects the ongoing main stories throughout the series.
Each story is good though and worth reading.
This book contains several short stories by Le Guin about Earthsea. They are exquisite. Le Guin writes so intimately and beautifully the place and characters just come alive. If you have not read Le Guin before this would be a good place to start.