I am a pretty much complete newbie and I have been working on a small 3D game, I want to make it so the player can choose between multiple different types of blocks and press a key to place them directly in front of them. I was thinking of making the block spawn a couple of digits in front of the camera because the camera is always facing where the player is-but I honestly don't really know where to start with this as there seem to not be any good tutorials out there on this sort of thing. Any help or suggestions would be appreciated.

You take the global_position of the camera then subtract global_transform.basis.z multiplied by the desired distance from it. That is your new spawn position. Then instantiate your placeable object scene, add it to the scene tree and set its global position to the spawn position.

    Zini
    What keyword/code would I use to make it so that when the player presses the input it would spawn the block?

      Define a suitable action (Project -> Project Settings -> Input Map), bind it to a key or some other input that should trigger the spawning.

      Override the _input function (https://docs.godotengine.org/en/stable/classes/class_node.html#class-node-method-input) and use the is_action_pressed function (https://docs.godotengine.org/en/stable/classes/class_inputevent.html#class-inputevent-method-is-action-pressed) on the provided event to check for the action you just created. Then continue as described above.