I want to talk about 압존법, which mean suppressing respectable form.
This rule is very weird rule, but it is correct Korea grammar. However, people do not use it very much, but all male Koreans (who went to military) understands this rule because they learn it in the military.
If you are talking to two people, person A and person B, and depending on their rank or age you suppress the respectable form.
For example, if a person A is your father, and person B is your grandfather. Situation is where your grandfather asks you what your father is doing, and he happens to be sleeping.
If you say "my father is sleeping now" 아버지(father) 자고(sleep) 있어요(ing) is the translation, but this is disrespectful, so you say "아버지 주무시고 계세요" which sleep and ing are replaced with honorifics or respectable form. However, if your grandfather, who is definitely higher rank(or age) than your father in your family, you skip or suppress the honorifics. So it is correct to say 아버지 자고 있어요, if the person you are talking have higher rank/age than the person you are describing.
In the military or work place, I will show you how it works.
You are a private and Person A is Sergeant and Person B is Captain and Person C is general, and just in case you do not understand the ranks, You(Private) < Sergeant < Captain < General
Captain : "what is A doing now?" A 지금 뭐하고 있어?
You : A병장 지금 자고 있습니다. "A(non-respectable - resp. form would be A병장님) is sleeping now.
Captain : 장군님은? "how about the general?"
You : 장군님은 주무시고 계십니다. "General is sleeping now"
You see how both the sergeant and the general is higher rank than you, the private. However, you skip the respectable form and honorifics for the sergeant since the captain is higher rank than the sergeant, so you lower the sergeant when talking to captain.
I know this is very confusing rule, and some Koreans get confused too.
Please let me know if you are unclear about this, and I will try to clarify it better!