en_tn_condensed/act/15/20.md

they must keep away from the pollution of idols ... sexual immorality ... strangled ... blood

Sexual immorality, strangling animals, and consuming blood were often part of ceremonies to worship idols and false gods.

pollution of idols

This possibly refers to eating the meat of an animal that someone has sacrificed to an idol or to anything to do with idol worship.

from the meat of strangled animals, and from blood

God did not allow Jews to eat meat that still had the blood in it. Also, even earlier in Moses's writings in Genesis, God had forbidden the drinking of blood. Therefore, they could not eat an animal that someone strangled because the blood was not properly drained from the body of the animal.