Literally: empty – heart/mind – wide/level – pocket/heart
Alternately: Open-minded and open-hearted. Without any bias, hangups, or pent-up bad feelings.
Notes: In this compound of compounds, 虚心 refers to a lack of prejudice or preconception, while 坦懐 is inner peace.
Replacing 坦 with homophone 担 (“carry on the shoulder”) is of course an error.