As Joe commented, the numbers seem to get larger as you move around the circle's edge like a clock face. Then the "hint" says "divided by their seat". So if the numbers are getting divided by something, and what they're divided by gets bigger as you move around the circle, the seat must be something that gets bigger as you move around the circle.
Next, starting with the 18 and moving clockwise we can see that each number is divisible by its position in that circle. So that's probably what seat means- position.
Trying the same thing for the outermost rectangle, we start with the 6 and move clockwise and get the same divisibility property. Same for the triangle, starting 20, same again for inner rectangle, starting 13. I'm just going with points on the corner of a shape being members of that shape, points on the sides are ignored, because otherwise we don't get this property of being divisible by incrementing numbers
So going through and dividing, the numbers become:
- Hexagon - 18, 1, 2, 2, 9, 20
- Outer rectangle - 6, 18, 15, 13
- Triangle - 20, 8, 5
- Inner rectangle - 13, 15, 15, 14
One of those comments mentioned converting the numbers by "a common method" and... well, they're all less than 26 now! Let's try turning them into letters alphabetically:
- Hexagon - RABBIT
- Outer rectangle - FROM
- Triangle - THE
- Inner - MOON
Rabbit from the moon