"es" as pronoun or not?

Hello everyone,

I've come across this sentence in lesson 9.4. 

I am wondering why it is “Es ist ein großer schwarzer Koffer…” and not “Er ist ein großer schwarzer Koffer…”. 

Is “es” here not a pronoun, and if not, what is it?

Hallo  AdnanO, 

Thank you for your question! Sometimes we need to use a ‘dummy subject’ or a filler when there is no subject accompanying the verb, and where the real subject is in a another part of the sentence. Es is needed to ensure the proper sentence structure without changing the meaning of the sentence or making the sentence invalid. 
Another example would be "Es schneit." - "It's snowing."  The es is not actually the one who is 'letting it snow' but you need a subject to make the sentence work.

You can also have es being used as a personal pronoun:
"Wir haben ein neues Auto. Es is schwarz." - "We have a new car. It is black." 
However, we only use es here because it is referring to the car which is neuter.
So when talking about the suitcase you could say:
"Ich habe einen neuen Koffer. Er is schwarz." - "I have a new suitcase. It is black."

You wouldn't say "Er ist ein großer schwarzer Koffer." One might say it's "doppelt gemoppelt" which means saying the same thing twice over. Instead you could answer "Er ist groß und schwarz." - "It is big and black." However, that rule doesn’t apply when talking about people, e.g. 
“Er ist ein großer starker Mann.” - “He is a tall strong man.”
”Sie ist eine kleine zierliche Frau.” - “She is a small petite woman.”

Hope this helps!

Viele Grüße, 

Julia