The :Ceil(), :Floor(), :Abs() and :Sign() methods for Vector3 / Vector2 are not documented in the api.
Here is where the methods are listed and these methods can not be found here:
https://create.roblox.com/docs/reference/engine/datatypes/Vector3#summary-methods
And here is how the methods act and what they do:
local exampleVector = Vector3.new(4.67, -23.32, 86) --this can be a Vector2 aswell
--Vector:Ceil() -> Returns a new Vector that applies ceil to each component of the original vector
print(exampleVector:Ceil()) --> (5, -23, 86)
--Vector:Floor() -> Returns a new Vector that applies floor to each component of the original vector
print(exampleVector:Floor()) --> (4, -24, 86)
--Vector:Abs() -> Returns a new Vector that has the absoulute value of the original vectors components
print(exampleVector:Abs()) --> (4.67, 23.32, 86)
--Vector:Sign() -> Returns a new Vector that has the original vectors components direction (-1, 0 or 1)
print(exampleVector:Sign()) --> (1, -1, 1)
sorry if i explained it in a weird way…