Since you asked so nicely I will try, just the once, to help.
When salts dissolve in water they dissociate into ions. The salt no longer exists as an entity.
Sodium Chloride for instance dissociates into sodium and chloride ions. The sodium forms positive cations and the chloride negative anions.
This you probably already know.
You may also know that when two ions from an insoluble compound meet in solution they precipitate out as a solid.
Sodium has the property that pretty well all its compounds are highly soluble.
This is not true of other common minerals.
In natural waters there are many different ions, both cations and anions dissolved.
Some anions result from the solution of carbon dioxide from the air to form carbonate anions.
Sodium carbonate is soluble
Calcium sulphate - gypsum - is soluble, but calcium carbonate - limestone is insoluble so calcium is removed from the solution via the carbonate route.
Many other mineral carbonates are also insoluble.
As a matter of interest, even sand (silica) is a bit soluble over geological timescales.