Gross motor skills are those involving large muscle movements, such as independent sitting, crawling, walking, or running. 
Deficiencies in Goss Motor Skills might include poor co-ordination, poor balance, difficulty with hand eye coordination tasks and movements that lack fluency.
There are many resources that assist development of these skills, have a look at these resources.

Calming Toys | Chewing Toys | Fidget Toys | Fine Motor Skills
Gross Motor Skills / Kinetic |  Visual Stimulation / Lighting
Sound / Audio | Tactile Toys | Teens +

Helping Books