That is, only x number of y services can be performed in z period of time. That means that when you can now just go into your doctor and get, say, a mammogram done, you will instead need to sign up on a list.
In Canada, you generally have to wait 6-12 months for a mammogram, even if you have a lump. This person (second Google result for "canada mammogram wait") was 34 and had a lump; she could not get approved for a mammogram until she had an ultrasound, which itself a had 6-month wait. That's the difference between easy treatment with little or no side effects and go home and wait to die.