Who doesn't remember this old favourite? Mine used to be red, blue and yellow - mind you that was 40 years ago.
Shape sorters are classic toddler go to toys. They are fun and keep little fingers and minds busy. Your child will learn hand-eye coordination and problem solving skills (15-18 mths) and shape names (2 yrs or so).
Don't be surprised if your toddler just plays with the pieces at first, he may need a little help. Take the simpler shapes, like circles and squares, and show him how they fit into their holes. At first, he'll try jamming pieces in willy-nilly. Gently guide his hand until each shape fits. Soon, he'll be sorting like a pro!
My little 14 month old only just got a couple of pieces in with a bit of help, but absolutely loved running around the house with the hot pink shapes in her own little bucket, pouring them out and putting them back in again. Maybe we'll borrow it once more in a few months and try again.