A "cum laude" is an academic distinction. Back in paleozoic times when I was young , most people graduated from university with a "pass' degree which signified that they had been physically present for three years and had managed to stay out of jail. People who had done some serious academic work (about 20-30%) would get an "honours" degree. If you did outstanding work say 75% or more, you would get a designation "cum laude" ( with praise ): if you got 80% you would get a Magna cum laude (with great praise). And if you got a 90 you would get a "summa cum laude" (with highest praise).
Almost nobody in may day got magna or summa at a Canadian or British University. ( If you got a 75% average you were head and shoulders above the average), an 80% average was unheard of and a 90% was considered out of this world.
It varies from school to school, but it's usually based on GPA. Where I teach, the cutoffs are the same as the one tango14 mentions (3.50 for cum laude, 3.75 for magna cum laude, and 3.90 for summa cum laude).