Work
Los and las
When referring to more than one person or thing, el becomes los.
el bolígrafo
the pen
los bolígrafos
the pens
And la becomes las.
la carta
the letter
las cartas
the letters
What's the deal with su?
Su can mean a few different things! Context will help you understand which meaning is intended!
su dinero
her money
su negocio
their business
¡Su café, señor!
Your coffee, sir!