My child understands letters and numbers but finds it hard to grasp their meaning.

Being able to read or say letters and numbers, and understanding and using their meaning, are different abilities. Some children memorize the symbols first and are slower with meaning. When teaching, tie it to real objects, photos, and experiences. For numbers, actually count things; for letters, link them to familiar names and signs. Start from "10 candies" felt, rather than the symbol "10." Tying it to situations used in life (shopping, taking turns) helps it sink in with meaning.