MYOB => Mind Your Own Business

It rather sounds rude :( you can say "신경쓰지 않으셔도 됩니다," which means "you don't have to mind."

Basically, -십시오 is a polite command form. Instead of saying, "Focus!" It comes across as "Please focus."

I think 십시오 is like saying "please" and makes the overall feel of the sentence sound less rude...

-십시오 is a fomal imperative. So, when added to the end of a verb, like "집종하십시오" (verb "focus" + 십시오), it becomes a formal request, being translated here in Duo as "please, focus". Just a begginer, though. Hope you understood!

similar to 습니다 but this 십시오 is imperative

I think it makes it into a command

It's the honorific impeartive form and it's usually translated like "Please (V)"

하십시오 -Please do 가십시오 - Please go