"Do you hear me" and "I hear you"

[englishstudent]

Hi,

Please let me know if my understanding/observation is correct or not.

"Do you hear me?" is used when someone is asking if the
other person heard him/her.

The other person may answer -
"Yes, I hear you"

But sometimes, when one person is narrating some incident
from his life, or his view, the other person may say
something like this - "I hear ya (buddy)".
In this case, does it mean he is saying something like
"I know" or "I understand" ?
Can it also mean "I agree"?

Thanks

--
“I know you believe you understand what you think I said, but I am not sure you realize that what you heard is not what I meant.” - Richard M. Nixon

[mykwyner]

Your understanding is perfect.

Keep up the good work.

[englishstudent]

Thank you.