Right-clicking a marker in the timeline opens the marker context menu. From this menu, you can:

Locate to Here

Move the playhead to this marker's position.

Play from Here

start playback from this marker's position.

Move Mark to Playhead

Move this marker to the current playhead position.

Create Range to Next Marker

Create a range marker between this location and the next one along on the timeline.

Hide

Hide this marker from the view. It can be made visible again from the Window > Locations window or the Ranges & Marks list.

Rename

Change the name of the marker.

Lock

If this is ticked, it will be impossible to drag the marker's position; useful if you want to prevent accidental movements.

Glue to Bars and Beats

If this is ticked, the marker will maintain its position in bars and beats even if there are changes in tempo and meter.

Remove

Removes the marker.

There are also a few options in Transport > Active Mark. These options apply to the currently selected location marker, and move it to a nearby region boundary, region sync point, or to the playhead or mouse.