I believe that this question is asking whether or not table sugar is a mixture.
Table sugar, or sucrose, is not a mixture. It is a compound.
Let me start with a pure substance and work up from there. Elements are pure substances because they cannot be broken down any more. An element is made up of only a single kind of atom. The element gold is made up of gold atoms. Carbon is made up of carbon atoms.
A compound is made of two or more elements that have been chemically bonded/joined to each other. Compounds cannot be separated through physical means. Water is a good example of a compound. It is made of hydrogen and oxygen. A compound is what table sugar is. Sucrose is made of three elements: carbon, hydrogen, and oxygen. However, this information is true of a lot of sugars, so I will clarify. Sucrose is identified as C12H22O11.
A mixture consists of two or more elements that are not chemically bonded to each other. It could be separated by physical means. "Lucky Charms" cereal is a good example. It is a mixture composed of the cereal part and the awesome marshmallow part. Each "element" can be identified and separated from the other through physical means. Sugar can be mixed into all kinds of things to create a mixture or a solution, but the sugar itself is a compound.