If you hold down alt on Windows or Option on Mac you can click on the marker and split it. Then spread the halves apart. You can then go into the marker's panel an type the information that you would like to appear in the timeline.
You can't see the info as a marker by default is just at a frame. When you create the marker, you can press, m,m that will bring up the marker window, you can type in the marker info, and then make the 'Duration' something, like a second or 5, then the marker will have some width, and you can easily change that by dragging the marker handles to fit the text you want to see.