For example, to make the translateX value of pTorus1 always equal the translateY value of pCone2, type =pCone2.translateY in pTorus1’s translateX box. When you move the cone up and down in Y, the torus moves side-to-side in X.
When you type an expression into a text box in the Attribute Editor or Channel Box and press , Maya then shows the computed value with an purple background. You can’t edit values that are the result of an expression. To edit the expression, use the Expression Editor.