Bethel is a word from Hebrew that means "God's house".
It is a biblical city located north of Jerusalem, which was a place of high importance to the Israelites, where they worshiped God.
In the Bible, the origin of this city is explained in Genesis 28:17-19:
He was afraid and said: "This place is fearful! It is none other than the house of God; this is the door of heaven".
The next morning, Jacob took the stone he had used as a pillow, set it upright as a pillar, and poured oil on top of it.
And he named that place Bethel, though the city was formerly called Luz.
Given its meaning, Bethel is also a name related to several churches. There are Baptist churches with that name, but it is also a word used in other institutions (schools) or in companies, like publishing houses, for example.
In the case of Jehovah's Witnesses, Bethel is the name given to facilities where various functions related to religion, such as Bible study, are performed. People who work at Bethel are known individually as Bethelites or in groups as the Bethel family.