Glaciers - Ice Movement

Glaciers have existed on Earth for millennia, appearing stationary but actually moving downhill. This movement is due to the pressure at their base, causing some ice to melt and form meltwater, which acts as a lubricant. This reduces friction, allowing glaciers to move more easily. Many glaciers are now moving faster than ever, up to 50 meters a day, constantly changing and evolving.

Why do glaciers appear to be stationary despite moving?

What is a lubricant in the context of glacier movement?