Error in making a rotating collectible using a float

I am trying to make a rotating collectible coin in 3D for a platformer game, and I keep getting this error which I don't know how to fix.

Assets/Scripts/Rotate.cs(18,26): error CS1503: Argument 1: cannot convert from 'float' to 'UnityEngine.Vector3'

Here is my code:

public class Rotate : MonoBehaviour
{
    [SerializeField] float speedY;

    void Update()
    {
        transform.Rotate(360 * speedY * Time.deltaTime);

    }
}

I've tried doing it with a public float instead of a SerializedField, but as expected, didn't do anything.
I'm expecting for it to rotate at the speed given in the inspector for the item.

You haven't specified an axis around which you will rotate.
Transform.Rotate accepts Vector3 as an argument, and you provided float.

You could do:

transform.Rotate(360 * speedY * Vector3.up * Time.deltaTime);

or better use a Transform.Rotate(Vector3 axis, float angle) override:

transform.Rotate(Vector3.up, 360 * speedY * Time.deltaTime);

It is not possible to initialize a type 'type' with a collection initializer, because it does not implement 'System.Collections.IEnumerable' To use a collection initializer with a type, the type must implement IEnumerable. This error can occur if you are using collection initializer syntax when you want to use an object initializer. To correct this error If the type does not represent a collection, use object initializer syntax instead of collection initializer syntax. If the type does not represent a collection, modify it to implement IEnumerable . You can then use collection initializers to initialize objects of that type. If the type represents a collection and you don't have access to the source code, initialize its elements using their class constructors or other initialization methods.