a keeping: guarding given concrete shape, whether as custody, a watch, or an observed charge
This word is the noun that belongs to the verb "to keep" or "to guard." It names guarding made concrete: whatever is being kept safe or held fast, this word marks the keeping of it. In practice that comes out three ways, all one idea seen from different angles.
Sometimes the thing kept is a person, and the word means holding someone in custody, as when Joseph is put "in ward" in Egypt. Sometimes it is a place or a wall being kept, and the word means the guard or the watch set over it, as when Nehemiah stations men on the ramparts of Jerusalem. And sometimes what is kept is a duty rather than a person or a place, and the word means the observance faithfully carried out, as with the services kept up in the house of God.
The breadth is why English Bibles reach for so many words for this one term. It also sits close to the feminine noun (מִשְׁמֶרֶת), which leans further toward a charge or duty kept, especially in worship, while this word stays nearer the concrete guard or the place of custody.