Answer

A very good English book to start with is The Jain Cosmology by Colette Caillat and Ravi Kumar. It is an English-language work that presents Jain cosmology with text, interpretive notes, and reproductions of ancient manuscript paintings, which makes it especially helpful and visually engaging. ( books.google.com)

Explanation

If you want a more scholarly and philosophical book, Cosmology: Old and New by G. R. Jain is also a strong choice. It is described as a modern commentary on the fifth chapter of the Tattvārthādhigama Sūtra and includes a comparative discussion of Jain cosmology and modern science. ( jainqq.org)

Spiritual Understanding

For understanding Jain cosmology in a clear way, The Jain Cosmology is a gentle place to begin, while Cosmology: Old and New is better if you want deeper doctrinal study. Both can help you appreciate the Jain vision of an eternal universe governed by its own natural order. ( encyclopedia.com)

Takeaway

If you want just one recommendation, start with The Jain Cosmology. If you want a deeper study afterward, read Cosmology: Old and New.