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The & symbol creates a borrow. A shared reference such as &str permits reading but not mutation, and it does not own the value it points to. Passing a reference avoids a move, so the original binding remains usable after the call. Later ownership lessons add the precise aliasing rules and mutable references.
In the example, name owns a String. Passing &name to length creates a shared borrow, and the parameter text: &str lets the function read the bytes through that borrow. length returns a usize, not the text itself. After the call ends, main still owns name and can print it. No second owned String had to be made for this read-only question.
A reference is valid only while the value it refers to is available. Rust checks that relationship so code cannot keep a pointer into a value that has already gone away. Shared references permit reading; mutation through a shared reference is not allowed.
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