When you say that someone makes no bones about something, what you mean is that the person is very frank about it. He speaks plainly, and does not attempt to hide the truth. For example, if a person makes no bones about a scandal in his past, he talks about it candidly at times, leaving the listener embarrassed!
Example:
The teachers made no bones about their dissatisfaction with the contents of the article.
Radha made no bones about her dislike for crossword puzzles.

 Some scholars believe that the idiom comes from games played with `dice'. During the early 14th century, dice were made from bones. Therefore, it comes as no surprise that the slang term for these small cubes was bones. I understand that even today, it is common practice among gamblers to talk to their dice and blow kisses on them before throwing them on the table. When a person makes `no bones about it', he rolls the dice without really doing any of these things. In other words, he doesn't plead with the dice to give him a particular number. This is just one of the explanations for the origin of the idiom.