Struct for PlayerInput - Tanks vs Zombies from Epic

Dear experts,

I am currently doing this tutorial Tanks vs Zombies and I am on part 2 now (C++ Tanks vs Zombies | 02 | Live Training | Unreal Engine - YouTube)
At 32:30 they start creating a struct to handle the PlayerInput, but they don’t really explain why we do this with a struct.
Can anyone explain that to me please?

Thank you, Peter