This is the 220th most frequent Hebrew word.
בבתי
"In my houses" or "in the houses of."
Here, "בבתי" is a contraction of "ב + בתי", meaning "in the houses of" or "in the institutions of," referring to 'schools'.
בבתי הספר לומדים התלמידים מקצועות רבים.
In the schools, students learn many subjects.
In this case, "בבתי" refers to "in the homes of," indicating possession or association with the residences.
בבתי המגורים שלנו יש גינה גדולה.
In the houses we live in, there is a large garden.
Here, "בבתי" is used to mean "in the houses of," specifically relating to religious institutions, namely 'synagogues' in this instance.