When it comes to the biographies of the Prophet Muhammad ﷺ, there are many available for different levels. But If you are new to the life of the Prophet ﷺ and want to deepen your understanding of His subliminal life.
I would highly recommend you to start with “When The Moon Split: A Biography of Prophet Muḥammad ﷺ by Safiur Rahman Mubarakpuri.” This book is easy to read and follow. The author doesn’t go to unnecessary details, that’s the reason its perfect for beginners and new Muslims. And at the end of each chapter there are lessons and morals from the seerah, followed by questions section to test your comprehension.
After finishing this book, you can start with “The Sealed Nectar by the same author” for more details on the life of Prophet Muhammad ﷺ.