Did you say “lbs”? Congratulations, you are correct.
Now, where does the abbreviation come from?
It’s rather curious. None of the letters (l-b-s) appear in the word “pound.”
What should be more curious is why you have never inquired into the matter (provided that is you don’t know the answer).
It also begs the obvious question: What else do you “know” but have little understanding of where that knowledge came from?
P.S. I’m sure you’d like to know the answer of where the abbreviation came from but I’m not going to tell you. You need to research the answer yourself. Why? Because I once read a quotation that has always stuck with me: “The greatest scandal in education is this: Once you teach a person something, you deny that person the opportunity to discovery the answer themselves.”