At 2 years old, the child's vocabulary consists of fewer than 10 words.
If your child does not understand speech (speech comprehension standards are below).
No phrases by 2.4 years old (this is the lower limit of the norm).
If a child is 3 years old and speaks their "own" language, others may not understand it.
Speech Comprehension Norms:
Understanding speech begins to develop almost immediately after birth, and the child's behavior can indicate their development.
3-6 months: The child listens to voices, primarily the mother's, and responds to intonation.
6-10 months: The child understands familiar words and phrases ("Where's dad? Give me your hand. No").
10-12 months: The child understands the names of toys.
12-14 months: The child recognizes toys in pictures.
15-18 months: The child recognizes toys in story illustrations.
1.5-2 years: The child understands two-step instructions ("Go to the room and bring the book").
2.5 years: The child begins to understand the meanings of prepositions and can answer questions like "What is the book lying on?" The child also begins to understand cause-and-effect relationships (e.g., "Vitya hit Petya. Who is the bully?").
3 years: The child understands short stories and can retell them or answer questions about the text.