Your little angel has now become smart enough to recognise things as per their appearance. This is the age when your kid is growing not only physically but mentally and emotionally too. Your kid now associates things as per their shape and color. The appearance of objects is what draws your kid towards them. Your kid uses his sense while describing an object.
What you need to do
First and foremost being every child is different so there has to be no comparison with other kids. Try analysing your child's potential and invest your time and energy in enhancing those skills. He has developed analytical and cognitive skills by this time and this the time when he will associate various objects with different shapes.
Your kid during this time will be able to draw basic shapes like a circle, straight horizontal and vertical line, a star etc. whenever your kid brings in something on a piece if paper or when he associates TV or ball or his favorite toy with a shape like a circle square or a 'V'even if it is wrong don't disappoint him or don't discourage him by criticising rather encourage him to follow the same route and make it a habit of making him learn these things through educational videos floating on internet or by getting him certain books having loads of pictures in various colors shapes and their favorite pets or cartoon characters. The other way is to read many story books and learning books which enhances his vocabulary and strengthens his imagination. This is the way your kid will learn the things really fast.