what are the gliding movements at the shoulder(glenohumeral joint)?
I don’t know what you mean by “gliding movements.” Being a ball & socket joint, flexion and extension in the sagittal plane, abduction and adduction in the frontal plane, horizontal flexion and extension, and internal and external rotation the humerus fully adducted as well as through up to about 130 degrees of humeral abduction. And of course there are many degrees of glenohumeral movement between pure planal movements.
Take care.