This is the 750th most frequent Spanish word.
cosa
"Thing" or "object."
Here, 'cosa' acts as a general noun referring to an object or item.
Esa cosa es muy útil para la cocina.
That thing is very useful for the kitchen.
In this case, 'cosa' is used to refer to something whose specific name may not be known or mentioned.
No entiendo bien cómo funciona esa cosa.
I don't quite understand how that thing works.
'Cosa' here figuratively refers to a matter or thing, emphasizing its abstract use.