Don't be concerned yet. It's a subjective test whereby educators and other professionals try to label your child. I believe each child is unique with pluses and minuses that create a special and interesting personality. The screening is for autism and other syndromes and conditions at different ages, especially to get a general idea of how the child will fit into a learning situation. The parents meet with a screening professional who will go over the score and various parts of the screening.
Many skills (expressive language, gross motor, self help, socio-emotional, etc.) are tested (feeds self cracker, sits unsupported, watches face for clues, etc.) and assessed with a perfect score of 100 if all skill levels are met. (It would be a rare 2 y/o who would get a perfect score! Some tasks are quite difficult, such as stand or hop on one foot.)
Children develop at their own rate and each is different. Boys tend to lag behind girls, and two-year-old children are just beginning to move out into their world. The average score for toddlers (11-23 months) is 40/100. Your nephew's score of 32 is slightly below this, and, instead of creating worry and panic, the screening counselor will advise his parents to bring him in again for retesting at a future date, probably within a year. The at-risk score is anything less than 18.
Your nephew's parents will be given a list of tasks and skills appropriate for his age, so that they can practice knowing where his ears and other body parts are, how to build a tower of blocks, can play games like peek-a-boo, practice following directions, etc.
I taught preschool for several years and was always amazed that so many 4 y/os did not know which hand was right or left, or could not follow three directions in a row (e.g. stand up, touch your nose, clap your hands). These kids were not autistic nor did they have learning problems. It was just that no one had ever thought to clue them in on right-left or to ask them to follow three directions in a row.
The main thing is that your nephew gets lots of mental stimulation and together time with other children and adults, learn how to socialize, and be sung to, told stories to, read to, played finger games with, taken on walks or to the grocery store or to the mall with lots of conversation about what is seen and heard and smelled.