Così means “in this way” or “like this”.

So the opera title “Così fan tutte” means “All [women] act like this”.

If you are buying things in a shop and the shopkeeper says “Poi?” or “Altro?” meaning, “Anything
else?” you can say,

“Basta così” or “Va bene così” to mean, “That’s all”.

“Così così” means “So so” when you want to tell someone how you are.