Read verses 6-7
From all the men selected out of Israel, some were specifically taken from Judah. Daniel, Hananiah, Mishael and Azariah were among the Judean captives. The priority to indoctrinate these men was to first change their names. Remember the king wanted to erase their identity, so their names were changed.
Daniel which means “God is my judge” was changed to Belteshazzar which means “a prince of Bel”. Bel being the chief god of Babylon and the god Nebuchadnezzar worshipped.
Hananiah which means “the Lord shows grace” was changed to Shadrach, Rak was the name of the Babylonian sun god or “messenger of the sun”.
Mishael which means “who is what God is” was changed to Meshach meaning “Who is Aku” or god of the moon.
Azariah means “the Lord helps” and was changed to Abednego meaning “servant of Nebo” the god of science and literature.
It’s interesting that we are most familiar with Hananiah, Mishael and Azariah as Shadrach, Meshach and Abednego but Daniel’s original Hebrew name stood through time. When Daniel stood before kings, he used the name Belteshazzar. However, Daniel himself refused to use this name when he wrote his book. He chose to use his Hebrew name, Daniel and was determined to not lose his Jewish identity. He refused to be reconditioned.