Translation
and those who use this world, as those who don’t use it to the full, For the present form of this world is passing away.
Paraphrase
If you are among those who take advantage of the opportunities this world offers, you should do so in a limited manner and not be like those who want to take advantage of every opportunity they see and do so to the greatest extent. Hopefully you understand that this world, and the opportunities it offers, won’t last very long (but spiritual work will last forever.)