You shall not lie with a male as one lies with a female; it is an abomination." (Leviticus 18:22)
The literal commandment is that a man must not lie with a male as one lies with a female.
Messiah implicitly affirmed this commandment when He spoke about the Law:
"Do not think that I came to abolish the Law or the Prophets; I did not come to abolish but to fulfill. For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke shall pass from the Law until all is accomplished. Whoever then annuls one of the least of these commandments, and teaches others to do the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven. (Matthew 5:17-19)
The physical intimacy of sexual union between a man and woman (husband and wife) provides a physical picture of the spiritual intimacy that is supposed to exist between G-d and humanity and between Messiah and the bride of Messiah (the assembly of believers).
When that physical intimacy is corrupted with homosexual relations then the picture is defiled and the message is corrupted. In the words of this passage of Scripture, it becomes an "abomination".
Just like there are certain animals that were not created to be eaten, there are certain people that were not created to be married (the only context in which sexual intimacy is permitted). People aren't supposed to eat pork, shellfish, cats, or dogs. Men aren't supposed to marry their sister nor are they supposed to marry other men.
In a similar fashion, the Messiah is for salvation. There is no other part of creation intended for that purpose.
Messiah fulfilled this commandment by not having homosexual relations.
The traditional observance of this commandment is found in its literal sense: men not having homosexual relations.
We are able to fulfill this commandment today and men should not have homosexual relations.