Crouching is bending or stooping down low to the ground. Crouching can be very similar to squatting. The man in the picture is crouching down so he can take a photograph of something from a good angle.
You say ouch! when you hurt yourself. The person in the picture has a caltrop stuck in their finger. Ouch!
A pouch is a type of small bag that opens at the top. Pouches are often a shape that has a rounded bottom. Some animals, called marsupials have pouches.