Here's how it breaks down:

* Na₂CO₃: This represents the sodium carbonate part, where:

* Na: Sodium (symbol Na)

* CO₃: Carbonate (symbol CO₃)

* ·10H₂O: This indicates that the compound contains ten water molecules (H₂O) for each formula unit of sodium carbonate. The "deca" prefix in "decahydrate" means ten.