By this age your child is able to draw figures using dots as he is now familiar with letters, numbers and objects around him.
What you need to know:
As a parent you, should understand such activities show forward progress over time. This activities helps in the development and enhancement of your child's direction following and reasoning abilities. And also fine motor skills while holding crayons or pencil. So to encourage drawing and writing skills you can make this activity a regular part of playtime for your child. You can start with simple shapes like square, circle, oval or letters and numbers. when moving to complex figures you can number the dots in sequence or draw few lines as hints. Try to include more of drawings that represent objects that are meaningful to him in his daily life.