What the account book contains and why did Billy Bones write it? And also, can someone name a few themes we can find in treasure island? I will need it for my exam prep, Thanks!

From the text:

On the first page there were only some scraps of writing, such as a man with a pen in his hand might make for idleness or practice. One was the same as the tattoo mark, “Billy Bones his fancy”; then there was “Mr. W. Bones, mate,” “No more rum,” “Off Palm Key he got itt,” and some other snatches, mostly single words and unintelligible. I could not help wondering who it was that had “got itt,” and what “itt” was that he got. A knife in his back as like as not.

“Not much instruction there,” said Dr. Livesey as he passed on.

The next ten or twelve pages were filled with a curious series of entries. There was a date at one end of the line and at the other a sum of money, as in common account-books, but instead of explanatory writing, only a varying number of crosses between the two. On the 12th of June, 1745, for instance, a sum of seventy pounds had plainly become due to someone, and there was nothing but six crosses to explain the cause. In a few cases, to be sure, the name of a place would be added, as “Offe Caraccas,” or a mere entry of latitude and longitude, as “62° 17′ 20″, 19° 2′ 40″.”

The record lasted over nearly twenty years, the amount of the separate entries growing larger as time went on, and at the end a grand total had been made out after five or six wrong additions, and these words appended, “Bones, his pile.”

“I can’t make head or tail of this,” said Dr. Livesey.

“The thing is as clear as noonday,” cried the squire. “This is the black-hearted hound’s account-book. These crosses stand for the names of ships or towns that they sank or plundered. The sums are the scoundrel’s share, and where he feared an ambiguity, you see he added something clearer. ‘Offe Caraccas,’ now; you see, here was some unhappy vessel boarded off that coast. God help the poor souls that manned her—coral long ago.”

Important themes include honor, adventure, coming of age, and conflict.