This item is just a flavor item, it doesn't tie into any quest. It's safe to delete from your inventory.

This book is a reward from this quest: https://vanillawowdb.com/?quest=5128 https://vanillawowdb.com/?quest=5128 .
You will get it in your mailbox after a day or so. I suggest you read it, if you're even a bit interested in background and lore. I like how Blizzard takes the time and effort to actually add some background to certain enemies (like the Winterfall in this case).

I just thought it was cool that they would do that. Ya the book makes it like there is more but still not many people send me things in the mail. I thought that was neat.

If anyone cares, book reads:<div class=""quote"">Page 1
Attackers... From all sides.

Can see it in their eyes. Timbermaw are evil enemy.

Must protect tribe. Must protect Winterfall. Must drive intruders from our land.

Page 2
Snow, blinding...

Must protect tribe. Make them strong. Be strong.

Do not know...

Page 3
Firewater.

Make more. More firewater.

Firewater make Winterfall strong. Defeat our enemies.

Winterfall have no ally. Winterfall are strong. Have great power.

Page 4
More. Must have more...

Winterfall... not... weak...

Comes in the mail sent from http://mop.aowow.org/https://vanillawowdb.com/?npc=10920 Kelek Skykeeper saying:<div class=""quote"">It took much time to translate the High Chief's text. I was dismayed by what I found. High Chief Winterfall was in an extreme state of paranoia in his last days and was addicted to a substance he called ""Firewater"". He believed that all creatures were his enemies. Well, I will let you read it for yourself -- I have included a translation of his words with this letter. If you are ever in need, please visit me again.