Numbers 21

"the soul of the people became very discouraged on the way...Then the Lord said to Moses, “Make a fiery serpent, and set it on a pole; and it shall be that everyone who is bitten, when he looks at it, shall live.” vv.4,8

Read chapter 21
The fiery serpent on a pole seems like another "golden calf" type idol that they would worship instead of God, but we see that the Lord is the one to tell them to make it.  Now make sure you read the whole chapter or at least the context because between the two verses I put above there's a lot that happens: the Lord sends down fiery serpents to bite and kill the people.  All this came about because the people became discouraged and complained against the Lord and Moses.  It reminds me of Hebrews 12:3, "For consider Him who endured such hostility from sinners against Himself, lest you become weary and discouraged in your souls." And the verse just before it tells us how 12:2, "looking unto Jesus, the author and finisher of our faith."
Well back to the serpent on the pole, we can see that this is a type of Christ of Jesus crucified on the cross.  And just as simple as it was for them to just have to look at it and they would live, so is our salvation unto everlasting life by believing Christ died for us on the cross and that would make us saved.  I'm sure you've seen an ambulance before, have you ever noticed the red cross on it?  There's the snake on a pole, just like here in Numbers, a sign to make someone alive.

Have you become discourage in your soul?  How can you look to Jesus to receive renewed life in Him?