The term "keeper" can have several different meanings depending on its context.
In a general sense, it refers to someone who is responsible for maintaining or preserving something. For example, a museum curator might be called a "keeper of artifacts." In this case, the word keeper means that the person has the responsibility to preserve and protect the items in their care.
Another meaning of the term "keeper" refers to someone who is responsible for maintaining or preserving something else - such as an animal in a zoo or wildlife park might be called its "keeper." In this context, keeper means that the person has the responsibility to take care of and look after the animal.
In some cases, the term can also refer to someone who is particularly skilled at their job or task. For example, a soccer team's goalie may be referred to as its "keeper." In this context, keeper means that the person has proven themselves to be very good at what they do and are trusted with an important role on the team.