It's true that you spoke to us in French. I apologize, Mrs. Shanahan.
Federal budgets operate on an annual cycle. As you know, at the beginning of each year, Parliament must approve each institution's budget. However, a department's work doesn't necessarily end on March 31, since some projects are ongoing, for example.
So the institution plans what it thinks it can spend during the year, but it's not unusual for actual expenditures to vary. This doesn't mean that the expenditures aren't made, but perhaps they will only be made the following year.
Sometimes funds are simply not used. For example, this year the amount of money that hasn't been spent is $36 billion, if I remember correctly. The net carry-forward is about $14 billion, which is money that will be frozen and then carried forward to next year's budgets.
Some departments, including Infrastructure Canada, are responsible for—