You can use really to emphasize a statement.
I'm very sorry. I really am.
我很抱歉。真的。
You use really when you are discussing the real facts about something, in contrast to the ones someone wants you to believe.
My father didn't really love her.
我父亲实际上并不爱她。
People use really in questions and negative statements when they want you to answer 'no'.
Do you really think he would be that stupid?
你果真认为他那么蠢吗?
If you refer to a time when something really begins to happen, you are emphasizing that it starts to happen at that time to a much greater extent and much more seriously than before.
That's when the pressure really started.
那是压力真正开始的时候。
People sometimes use really to slightly reduce the force of a negative statement.
I'm not really surprised.
我其实并不惊讶。
You can say really to express surprise or disbelief at what someone has said.
'We discovered it was totally the wrong decision.'—'Really?'
“我们发现那完全是个错误的决定。” “真的吗?”