An Amiga outputs either NTSC or PAL, depending on the region it was made for. So with the right cable, you can just plug it in to a TV made before the mid-2000's. Later models also supported VGA.
Its outputs include analog RGB, so if you had a VGA monitor that could sync to NTSC or PAL vsync signals, you could get a usable image. IIRC most monitors could not though.