What is naco2 + cocl2 equal to?

You should write your formulae the right way, capital letter for the first letter of the symbol and small letter for the second letter together with the correct number of each element.

Now to your question, you should know the solubilities of salts.

Example: All carbonates () are insoluble in water except sodium, potassium and ammonium carbonates (the three that you'll be encountering most frequently, there are others though, that you don't need to know for now).

All chlorides are soluble in water, except silver and lead (II) chloride.

Check your equation, there is a carbonate, and a chloride.

Sodium carbonate is a soluble salt, so is cobalt carbonate.
If they react, what could be formed? Sodium chloride and cobalt carbonate.
Since cobalt carbonate is insoluble in water, it will be precipitated out, leaving sodium ions and chloride ions behind. So you get: