“Sorrow.” The Hebrew word is kaas (#03708 כַּעַס), and it can mean sorrow, anger, vexation, grief, frustration, etc., depending on the context (it is “anger” in Ecclesiastes 7:9). Here the context is unclear, in part because the word translated “sadness” in the phrase “sadness of the face” is much more often translated “evil” or “bad.” Many versions have “Sorrow…sadness” (ESV; KJV; NAB; NASB; NIV), because of the context about living and dying. But anyone who has dealt extensively with death knows that different people react differently and often people’s emotional state changes with time. Alternate but very acceptable translations instead of “sorrow” include “aggravation” (CEB); “grief” (HCSB); “vexation” (Darby); “anger” (Douay-Rheims); and “frustration” (NIV2011). Similarly, a “sad” face is literally “an evil face,” and it can refer to a sad face; a “sober” face (NET); a “troubled” face (Temper Longman), and even a marred face (Rotherham)—perhaps a face marred by weeping and being distraught in one’s soul.
Ecclesiastes 7:3 uses vocabulary that allows us to go deeply into the mind and heart of people who are experiencing death in some close or visceral way, and/or people who contemplate death deeply and allow it to affect their heart and change it for the better. Living with the end in mind is always better than ignoring the reality of life (cp. Ecc. 7:2).
“the heart is made good.” Like the previous phrases in Ecclesiastes 7:3, the fact that the heart is made good” has a great depth of meaning. The word translated “good” can be translated “well” or even “better,” and the heart can be made good or well as people deal honestly with life and death and do not live in denial of what will certainly come in the future. When we are honest with life and death, and also with the everlasting life offered by God, and do not hide from or ignore reality, our heart changes for the better, and that fact is reflected in many of the various English versions. The NLT paraphrases the Hebrew text, and has “sadness has a refining influence on us.”
Although some English versions say the heart will be made “glad,” that is likely not the emphasis in the text. Sadness does not make people “glad,” but handled well it can deepen their heart and make it good.