If a resource is non-renewable does it mean that there is only a small quantity of it?

Not necessarily; a non-renewable resource can exist in large quantities, but it is finite and cannot be replenished on a human timescale once depleted. Examples include fossil fuels like coal and oil, which may be abundant but take millions of years to form. The critical issue with non-renewable resources is their eventual exhaustion due to continued extraction and consumption, rather than their initial quantity.