There is a well organised recorded playlist from Swami Omkarananda in their Youtube Channel. (Search for Swami Omkarananda Bhagavad Gita)
The lectures are delivered in a simple (often humour included) way.
In addition to this, Swamiji insisted on beginning with Gita Mahatmyam (Vaaraha Puranam, Dhara-Vishnu Samvade) and Gita Dhyaana Shlokam (Sripaada Madhusudana Saraswati) as pre-requisites even before starting with the Gita.
He can simply listen to this playlist or if he is more interested, can memorise them.
May he have fun in this journey.
May the grace of Krishna always be with him.
Swamiji is no more, but he lives on through his lectures.