“We’re down 4% over last year.”
You're giving a presentation on your company's financial performance. You're showing a chart which compares this year's earnings with last year's. You explain that the company made a little less this year.
We’re down 4% over last year.
In business, people sometimes talk about sales or other important numbers this way:
We're at 3 million for the quarter.
What this means is:
(Our sales are) at 3 million for the quarter.
People also say "We're up", "We're down", "We're flat", "We're growing", etc.:
We were growing by about 10% per month, but we're flat this month.
You can compare numbers for one time period to a past time period with the word "over":
Profits are up 10% over last quarter.
This means "Profits are 10% higher than they were in the last 3-month period."