Hopefully your child will be playing. How much they will be learning through that play will depend on several factors- mostly the professionalism, qualification, experience & passion of the staff, peers, provision and environment.
It's very easy to write 'play' off as a trivial activity, something that means the means the opposite of 'work' or structure. However in an ideal setting- your child will have choice over a wide range of open-ended activities & materials, both indoor and out, and adults who observe & respond to his interests, extending his thinking, challenging, and supporting him in becoming independent in a wide range of skills & knowledge.
So what might look like running around in a chasing imaginative game will likely involve most of the curriculum, because it will generally always at least involve: negotiation with peers, understanding social communication: verbal & non-verbal. , physical skills (negotiating pathways, climbing, running, jumping, fine motor- grasping, throwing, pulling) Judging timing, distance, observing the effects of physical activity on our bodies, vocabulary and language... The list goes on really.
Play can easily cover the curriculum. Children don't need to be sat on the mat listening to an adult to be learning. They can learn so much more of the adults have set up an enabling environment, and also are available to further extend and support their interests.