The solute is the substance that gets dissolved in a solution. So, in the case of sodium chloride or table salt, it will get dissolved in a very familiar solvent, such as water #(H_2O)#.
Sugar can also be dissolved in water, particularly in tea, to make our tea sweeter and for some people, easier and tastier to drink.
Carbonated water is water with #CO_2# dissolved in it. It can be partly acidic though, since aqueous carbon dioxide will react with more water molecules to form carbonic acid #(H_2CO_3)#, which is responsible for the acidity of the drink. Luckily, it is a weak acid, so not a lot of harm will be done to the body once ingested.