How to make text appear when other text is clicked?

I have created 3d text and would like another 3d text to appear when the first 3d text is clicked.

Make sure the one you want to click on has a collider. Turn off the renderer on the one that starts out hidden. Then you can use something like this:

var goOther : GameObject;

function OnMouseDown(){
goOther.renderer.enabled = true;
}

You’ll drag your hidden game object to the goOther variable in the inspector. There are other ways, but this s starting point.