If you describe someone as honest, you mean that they always tell the truth, and do not try to deceive people or break the law.
I know she's honest and reliable.
我知道她是诚实可靠的。
If you are honest in a particular situation, you tell the complete truth or give your sincere opinion, even if this is not very pleasant.
I was honest about what I was doing.
我对我所做的一切毫不隐瞒。
He had been honest with her and she had tricked him!
他对她是真诚的,而她却欺骗了他。
You say 'honest' before or after a statement to emphasize that you are telling the truth and that you want people to believe you.
I'm not sure, honest.
我不能肯定,不骗你。
to be honest
You can say 'to be honest' before or after a statement to indicate that you are telling the truth about your own opinions or feelings, especially if you think these will disappoint the person you are talking to.
To be honest the house is not quite our style.
说实话,我们不大喜欢这房子。
honest to God
Some people say 'honest to God' to emphasize their feelings or to emphasize that something is really true.
I wish we weren't doing this, Lillian, honest to God, I really do.
我希望我们没在做这件事,莉莲,真的,我确实这么想。