'Sign' in the Bible

‘Then this shall be the sign [of these things] to you [Hezekiah]: this year you will eat what grows of itself, in the second year what springs up voluntarily, and in the third year sow and reap, plant vineyards, and eat their fruit.

Hezekiah said to Isaiah, “What will be the sign that the Lord will [completely] heal me, and that I shall go up to the house of the Lord on the third day?”

Isaiah said, “This will be the sign to you from the Lord, that He will do the thing that He has spoken: shall the shadow [indicating the time of day] go forward ten steps, or go backward ten steps?”