Let's see the definition of each concept:
An element is a substance only formed by atoms of the same element. For example, Na (sodium), O2 (oxygen), C (carbon).
A compound is a substance formed by the combination of two or more elements, through a chemical bond. For example, H2O (water), and CO2 (carbon dioxide).
A pure substance can be an element or a compound, which is alone in the media. For example, the O2 present in an oxygen bullet is pure, because it is only oxygen.
A mixture is when you have 2 or more elements or compounds present in the same media. For example, the air is a mixture of oxygen and nitrogen.
Then, the answer is that NaCl is a compound and a pure substance.