Can anyone eplain the relevance? of line moves

[veriableodds]

Using example from game in ncaaf this coming week
michigan @ minnesota
opens at MI-16.5 now at -20.5
-looking at the money 68% on MI

Question is what this would mean if the money was somewhat 50/50 split??

another example say NBA
line opens fav is -5 moves to -9 before gametime and the money is very close on both sides?? What does this mean?

never paid heed to this type wagering, but know some do
thanks
-veri-