"I am sorry."
I like to think of it as "unnskyld" is what you say as you cut through a crowd, and "beklager" is what you say when you actually bump into someone while doing so.
Unnskykd is for something wrong you did and beklager when apologising in general and for things you didn't cause.
We use Unnskyld like when we said, excuse me there is no room for you , But beklager when you do something wrong and you apologize.
Can I say "jeg ER beklager?" Would it be wrong? I'm not used to not using a substitute to "am".
It would be incorrect, yes.
Norwegian has one present tense, which covers both the simple present and the present continuous in English. Its structure mimics that of the simple present in English, so trying to apply that of the present continuous just results in gibberish I'm afraid.
Worked with (only) "unnskyld" for me just now.
But you would not say "jeg unnskyld" or "jeg unnskylder" if that is what you are trying to write.
"Unnskyld" is the imperative of "å unnskylde". You ask someone to forgive you, so the implied subject is "du" or "dere".
Another "false friend" for native germans. "Beklager" sounds an awful lot like "beklagen", which means "to complain", but can also be used as a way of saying "someone is sad", as in "Er beklagt den Verlust von..." = "He has lost ... (maybe a family member) and is upset about it."