I couldn't understand the meaning of this sentence. How can I say it in different way? It slashes a dent in the shipments.?

I don't understand it, either. As written, it makes no sense.
Unfortunately, without knowing what you are trying to say, I can only guess… perhaps:

1. negative affect on production:
"It slashes the number of shipments."
"It puts a dent in the number of shipments."

2. actual physical damage:
"It causes dents in the shipping cartons."
"It results in damage to the shipments."

Either somebody actually made a dent in a shipping box/boat, or it delayed the shipments

Your problem is that a slash and a dent are two different kinds of damage, so choose one.