5 Answers

It means to be hesitant to speak or act because of a moral or ethical conflict.
Some may know that they should tell the truth but hesitates because it may impact upon another person. Not knowing whether this would be best for that person or cause them problems; deciding what to do is the state of being reticent.

ret·i·cence (rt-sns)n.1. The state or quality of being reticent; reserve.

2. The state or quality of being reluctant; unwillingness.

3. An instance of being reticent.

or what @daren 1 wrote....

Shy; unwilling and reluctant are good words Julie gave you, and Daren1 had another good explanation.
A person who is reticent can be a little annoying!  "Just do it!" comes to mind....

The state or quality of being reticent; reserve.2. The state or quality of being reluctant; unwillingness.

3. An instance of being reticent.

Reticent (adjective) - not communicative - not saying all that one knows - taciturn - reserved or perhaps to keep silent. Reticence is the (noun). He says it so reticently which is the adverb.