“Whoever is naïve.” Wisdom (Prov. 9:4) and Folly (Prov. 9:16) have the same invitation to the simple and ignorant, but their intent, and the end of accepting their invitation, is totally different.
“says.” The Hebrew is in the perfect tense as if it happened in the past. She continues her calling out, but it is clear she has been doing so for a long time. So in that sense, she is just like Wisdom, calling and calling for people to listen. The perfect tense verb is also used for Wisdom (cp. Prov. 9:4).
“sense.” The Hebrew word is leb (#03820 לֵב), which is often translated “heart,” but this is one of those cases where that translation would cause confusion. In modern English, the word “heart” usually refers to emotion or passion, but that is not its meaning here. The function of the brain was unknown in biblical times, so things that we generally assign to the brain, like thinking, attitudes, understanding, and good sense, were assigned to the heart. In this case, the naïve people lacked “good sense.” [For more on the Hebrew word leb and “heart,” see commentary on Prov. 15:21, “sense”].