Honesty: Someone is honest if he or she speaks the truth about his or her own beliefs (and feelings, desires, and values).
Note this does not imply (necessarily) that someone who speaks the truth about his beliefs also
speaks the truth about the reality his or her beliefs are about: One
may be quite mistaken about the real facts, even though one speaks the
truth about one's beliefs about them.
Then again, one's own beliefs are by oneself believed to be true or
probable, indeed also if they are not, and also if one has no evidence
that are. And incidentally, most of one's general beliefs (beliefs that
go further than merely reporting experiences: many of these are
formulated as generalizations involving every thing of some kind) are
not true but are at best probable, and that not because they may not be
true, but because one lacks the evidence to prove they are true (while
having evidence that - one believes - makes them probable).