What is meant by the small red square?

[Kashif1961]

Dear Members,

Somebody please help me regarding this red square in the attached file.

Aquil61

 

[m1b]

It means that there is at least one object on that layer selected. It is red because that is the color of the layer.

By the way you can alt/option click on that area in the layers palette to select all items of a layer or group, and by dragging the little square you can move the selected item(s) in the layer order, eg. move something to another layer very easily.