The scripture you site is found at: (1 Corinthians 15:58)"Therefore, my beloved brethren, be steadfast, immovable, always abounding in the work of the Lord, knowing that your toil is not in vain in the Lord." (NASB)
This indicates that whatever we do, in harmony with God's will, will not be forgotten by God. He sees it all (2 Chronicles 16:9) and will remember your good works.(Matthew 7:21-23)(Acts 10:1-4)
To do something in vain means that you do not succeed in doing what you are trying to do; to try in vain is to fail.
Indentured servants were forced into slave-like labor as a result of vain pursuit of a better life.
Except the LORD build the house, they labour in vain that build it: except the LORD keep the city, the watchman waketh but in vain.
in vain means the expected result is not going to happen
I think you mean "vain".
for no point
Vain means conceited, or it may mean to no avail. Here are some sentences.She tried in vain to stand on her head.He was as vain as a peacock."You're so vain!" (a song by Carly Simon)
To die in vain means that you died for a cause but your death did not change anything.
Without effect or to no purpose
Vain.
Vain
Obsessed with looks