You've been blessed by the frost giant Ymir. As an action, you're able to manipulate temperatures. For example:

You can lower the temperature of a room or specific object to freezing or below.
You can freeze an area up to a 5 foot cube to create a block of ice (does not work if there's a creature in the area you're attempting to freeze).
If there's an object or area that's already freezing or below you can raise it back to room temperature.
You can create small intricate shapes made from ice such as tiny sculptures or keys, or larger, less complicated ones like spheres or stalactites up to five feet in length.
You can change the color of any ice objects or surfaces you've frozen. I.e. creating a gem shape from ice then changing the color to resembles the gem's color.