First, there's gravity. You know, the thing that pulls everything down to the ground? Gravity makes the rotocopter fall in the first place. It's like the reason it goes down instead of up.
Then there's air resistance. It's like when you stick your hand out of a car window and feel the wind pushing against it. Air resistance is like that wind but for the rotocopter. It kinda slows it down as it falls.
Lift is the opposite of gravity. It's the force that pushes stuff up. The way the blades of the rotocopter are shaped and spin, they create lift, sort of like how an airplane's wings work.
Thrust is what makes the rotocopter spin around. When it's falling, the blades push air down, and that pushes the rotocopter up, but also spins it at the same time. It's like how a spinning top keeps going.
So, the forces are gravity pulling it down, air resistance slowing it down, lift making it go up a bit, and thrust making it spin. All those forces together make the rotocopter do its thing!