According to Moses, God wanted the people to make special curtains with blue loops on the edges to connect them together in a special way. This was to make everything look nice and stay in place, just like following instructions in building a big tent.
Exodus 26:4: And thou shalt make loops of blue upon the edge of the one curtain from the selvedge in the coupling; and likewise shalt thou make in the uttermost edge of [another] curtain, in the coupling of the second. [selvedge: an edge of cloth so woven that it cannot unravel]
While seemingly repetitive, it gives a different number for loops on the curtains, presenting a potential conflict in the amount or representation during retelling.
Exodus 36:12: Fifty loops made he in one curtain, and fifty loops made he in the edge of the curtain which [was] in the coupling of the second: the loops held one [curtain] to another.