"Wear your heart on your sleeve" means to be open and emotional, often showing your feelings easily and readily. It implies a lack of restraint and secrecy in displaying emotions.
Here are some examples of how the idiom is used:
* "She wears her heart on her sleeve, always letting everyone know exactly how she's feeling."
* "His emotional vulnerability makes it seem like he wears his heart on his sleeve."
* "Don't worry, I wear my heart on my sleeve, so you'll always know where you stand with me."
The idiom originates from a Shakespearean play, "Othello", where a character describes his feelings as being "on his sleeve" for all to see.