요 and 니다 whats the meaning and use of this is korean?

They're how statements often end.

Both are two different ways (the first is a bit more informal - you wouldn't use it in writing) to say statements to an unknown audience or to someone who is higher in age or status or whatever than you.

the first one "yo" can make pretty much any sentence into a polite sentence if you just attach it to the end. For example:

밥 먹었어. (I ate, Bab mugutsuh) is informal.

밥 먹었어요. (I ate, Bab mugutsuhyo) is formal.

You could do that with lots of other sentences, but with "니다', you have to modify the last few characters of the sentence (you can't just add "yo" to it, yo.)

Oh yeah, there was some random story I heard in childhood of some servant who figured that since both 요 and 니다 are methods of making your sentence more polite, he decided to add both of them together. So it became 니다요. And if you say that to people in Korea, they won't think it unusual.

With the sentence "I ate", it would be

밥먹었습니다 (I ate, babmugutseupnida)

with 니다 (nida), or

or.... using both,

밥먹었습니다요. And you can guess how the last one would be read. Again, the "yo" can be just added onto the "nida", but it's kind of old practice to use both.

the second one is 'i don't know'