Acts 15:29 refers back to Leviticus 17 and 18, where the laws which apply to Gentiles ("strangers"/"alien") who have chosen to live amongst the Covenant people are given. In other words all the other ceremonial laws do not apply to the Gentiles living amongst the Jews. These laws can be seen to parallel the laws in Acts 15:29 thus:-
They should not eat ...
There is no external law that binds the Christian.
1 Corinthians 6:12 "All things are lawful to me," but not all things
do profit. "All things are lawful to me," but I will not be mastered
Romans 7:4 Likewise, my brothers, you also have been put to death to the Law through the body of Christ, for you to belong to another, to the One ...