I don't really understand your question. Are you asking about the type of trackside signals in use, the lights on front and rear of the trains, something inside the locomotives, or something else?
If you're asking about the trackside signals, then it's whatever the host railway uses. On most lines, it is the searchlight style with a single lamp per head indicating one of three colours (green, yellow, red). CN has started updating some of their operating signals to use a stoplight style with a three light green/yellow/red LED head.