The Second Commandment (or the latter part of the First Commandment for Roman Catholics and Lutherans) is found in Exodus 20:4,5 - "You shall not make for yourself a carved image, or any likeness of anything that is in heaven above, or that is in the earth beneath, or that is in the water under the earth. You shall not bow down to them or serve them…"
The word that the King James Version translates as “graven image” means an idol. The pagan nations surrounding Israel practiced idol worship. Nations and families worshiped and presented offerings to wooden, cast-metal, clay, or painted objects. They believed that these idols represented or were inhabited by a deity.
Anything can become an idol. New Testament authors warned believers against participating in the worship of physical idols and the demonic powers they represented. However, they make it clear that idolatry is the spiritually broader concept of prioritizing anything over God. Colossians 3:5 - Put to death therefore what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry. Those are not physical objects of worship, but the spiritual outcome is the same: idolatry is trusting an idol to bring us the security and happiness that we were made to find in God.
Are statues of saints, crucifixes, and icons (images of Christ and Saints) "graven images”? This debate has long created schisms in the church. Roman Catholic and Orthodox traditions hold that these are objects that are essential guides for veneration, rather than worship of the represented person. Christian iconography exploded after the adoption of Christianity by Emperor Constantine. After that, the church has experienced had many movements of aniconism where any religious images were prohibited, namely the Byzantine iconoclasm (literally, icon-breaking) and Calvinism. Aniconism is generally continued today by fundamentalist and evangelical churches.