It means is a. You could use it to say he is a lawyer, but you couldn't use it to say he is a little sick. Es is used like that to describe who someone is not how they are. There are many other rules as well.
"usted es un hombre" means "You are a man" in English..
es un dia mu lindo
"Es un libro" translates to "It is a book" in English.
"what is an earthquake"
It is not a pencil.
It means: "It's a sin"
Approximately "It's a beautiful day."
you really are a bad boy
is a player who loves all
it means Es un placer - my pleasure
He/she is a monkey.
You are a crazy man(boy).