The word translated "heart" here is לֵבָב, which is a word that does, in fact, refer to the organ that we call "heart". Here, the word is obviously being used metaphorically, just like we use "heart" metaphorically in English. But the key question is whether לֵבָב and "heart" are used metaphorically *in the same way*.

In this video, Dr. Kevin Grasso shows how this Hebrew word actually has a different metaphorical use than you might expect, and that there may be a better English word than "heart" to get its meaning across.