The most common type of Learning Disability is Dyslexia.

Dyslexia reults in a person having trouble understanding written language. 

Dyscalculia is where a person has trouble solving arithmetic problems and grasping math concepts.

Dysgraphia is where a person struggles to form letters or write within a defined space.

Auditory and Visual Processing Disorders: a person with normal hearing an vision nevertheless has difficulty understanding nd using verbal or written language.

Non-verbal Learning Disabilities: Specific disorders which originate in teh right hemisphere of the brain and cause problems with visual-spatial, intuitive, organizational, evaluative and holistic processing functions.

FYI: AD/HD is actually not a learning disabilty. It is, however, common in about 1/3 of the people with LD.