how can I print terminal text to a file?

I learned how to print command output to file. Example: ls > file path or echo "print to file" > text.txt. But say I am converting a video file to audio. The new mp3 goes to a file. This is normal. However, I want the stream of processing text that is produced on the terminal screen to go to a file. How do I do this? Apparently "command processing" text is handled differently than "command result" text.
Feel free to correct my terminology.