Well what does that verse mean to you?
To me it means we are not supposed to get dismayed at something we see in the sky.
Yeah, something we see in the sky: Lighting, a solar eclipse, etc.
God is telling Israel, through the prophet Jeremiah around 586 BC, to abstain from worshiping the idols and false gods of their neighboring nations.
"Learn not the way of the heathen"
These "heathen" nations worshiped things of nature. They were dismayed (terrified) of the forces of nature. So they would create gods for each of the forces of nature and worship them and sacrificed to them to calm these false gods, to calm nature.
God is telling Israel not to be terrified of these things that they see in the sky like the heathen do, because it is God who created nature and it is God who makes these things happen.
"be not dismayed at the signs of heaven; for the heathen are dismayed at them."
The rest goes like this:
"3For the customs of the people are vain: for one cutteth a tree out of the forest, the work of the hands of the workman, with the axe.
4They deck it with silver and with gold; they fasten it with nails and with hammers, that it move not.
5They are upright as the palm tree, but speak not: they must needs be borne, because they cannot go. Be not afraid of them; for they cannot do evil, neither also is it in them to do good.
6Forasmuch as there is none like unto thee, O LORD; thou art great, and thy name is great in might.
7Who would not fear thee, O King of nations? for to thee doth it appertain: forasmuch as among all the wise men of the nations, and in all their kingdoms, there is none like unto thee.
8But they are altogether brutish and foolish: the stock is a doctrine of vanities.
9Silver spread into plates is brought from Tarshish, and gold from Uphaz, the work of the workman, and of the hands of the founder: blue and purple is their clothing: they are all the work of cunning men.
10But the LORD is the true God, he is the living God, and an everlasting king: at his wrath the earth shall tremble, and the nations shall not be able to abide his indignation.
11Thus shall ye say unto them, The gods that have not made the heavens and the earth, even they shall perish from the earth, and from under these heavens.
12He hath made the earth by his power, he hath established the world by his wisdom, and hath stretched out the heavens by his discretion.
13
When he uttereth his voice, there is a multitude of waters in the heavens, and he causeth the vapours to ascend from the ends of the earth; he maketh lightnings with rain, and bringeth forth the wind out of his treasures. 14Every man is brutish in his knowledge: every founder is confounded by the graven image: for his molten image is falsehood, and there is no breath in them.
15They are vanity, and the work of errors: in the time of their visitation they shall perish.
16The portion of Jacob is not like them: for he is the former of all things; and Israel is the rod of his inheritance: The LORD of hosts is his name."
