I don't know Rust, and the only thing opaque to me in that line is the `'a` syntax. I suppose it is related to memory safety.

In plain English:

`search_entry_hashed` is a parametric function. It works in a type safe way on any kind of K and V. It takes as arguments a reference to a mutable hash table, a hash function and a key, and returns an `Entry` object whose precise type depends on the type of the parameters.

You could hardly express that more succinctly. You can't understand it by skimming it, but it is a complex definition.

In Rust it's unfortunately typical to give one-letter names to generic types. A verbose version could be:

   fn search_entry_hashed<'lifetime, KeyType: Eq, ValueType>
      (table: &'lifetime mut RawTable<KeyType, ValueType>, hash: SafeHash, key: KeyType)
      -> Entry<'lifetime, KeyType, ValueType>

Depends if you know Rust. The language can do things with types and memory that (say) something like Python or Ruby don't do, which means Rust needs extra syntax to mark those things. Most of the <> or ' are to do with types or memory safety.

It's alright.