This is a passage from the book The Silk Roads, A New History Of The World by Peter Frankopan, 2019:
The only difficulty, of course, was the native population, who “delight to tormente men in the most bloodie manner that may be; fleaing some alive with the shells of fishes, cutting of the members and joynts of others by peacemeale and broiling on the coles, eat the collops of their flesh in their sight whilst they live, with other cruelties horrible to be related.”
Following the reference, which you should always do if you want to know more about a quoted passage, we see that this is an excerpt from:
W. Bradford, History of Plymouth Plantation, 1606-1646, ed. W. Davis (New York, 1909), pp. 46-7
This quote is therefore from a text written in Early Modern English (EME). In EME, the spelling was far less standardized than it is today, so it's not uncommon to run into archaic, dated, or obsolete spellings of words (if you read the original text). Shakespeare, for example, wrote in EME, so most modern editors change the spelling to be more like today's. The author of The Silk Road has declined to modernize the spelling. Here are a few of the words that might be confusing and their modern equivalents:
In this case, fleaing is the present participle of flea, which is an obsolete spelling of flay ("to cut the skin off").