IPC Sections, Where Art Thou?

I've been banging my head over this one concept - what constitutes 'act of a person of unsound mind' under Section 84 of IPC? I know it's not a big deal for some, but honestly, I just haven't grasped it yet. Every explanation looks like a jumbled mess of exceptions, explanations, and 'ifs' in my notes. Online lectures are no help - power cuts, poor connectivity... it's like the universe is conspiring against me. Three days to go for AILET and I still can't get this right. My family thinks I can magically get them out of these traffic challans, but I'm stuck in a world of criminal law. Anyone, please tell me I'm not alone here?