If you wear your heart on your sleeve, you openly show your feelings or emotions rather than keeping them hidden.

My father was raised to be a tough guy, so he could never wear his heart on his sleeve.

You’d never be good at poker. You always wear your heart on your sleeve.

My twins are completely different. Shelly always wears her heart on her sleeve, so it’s easier to know if she’s having problems. 

I don’t recommend you wear your heart on your sleeve in this office. It’s an old boy’s club here and strictly business.

Tradução: ser transparente nas suas emoções, ser muito emotivo, exibir seus sentimentos abertamente.