You can see tremendous growth and development in your child about this time. Along with his physical development there is a growth in his thinking ability. He is now able to think creatively and apply logic in his daily activities.
What you need to know
There was a time when your kid was figuring out the difference between same and different and sorting things based just on shape and color. He may have understood that round shape means a ball. So when he saw an orange he would have said it is a ball. But now as he is able to think logically you will see him sorting things in a better way. He will now sort objects into groups that belong together. He will put all his balls in one group, his kitchen tools in another group and so on. As his language skills are also improving you will notice him finding the difference in similar sounding words like bear/pear, bed/red, and wood/good.
Because each child develops in his own particular manner it is difficult to say when exactly he will achieve the milestone. Guide him properly and help him understand the concepts which will benefit him when he goes to school.