A diminished 5th is the same as a diminished chord (B D F) without a seventh. Your link points out that it often is substituted for a dominant 7th and resolves to the tonic of the key. BDF, when played with a G in the bass, becomes a G7.

The root of a diminished chord generally leads to the root of the chord following it. So, a B diminished would resolve to a C. A D diminished would lead to an Eb and an F diminished would lead to an F#.

Diminished chords occur naturally on the seventh step of a diatonic scale (ti). The seventh step of a scale is also called the leading tone because it so desparately wants to go back home to the tonic. Sing "Shave and a Haircut" and stop on the two before bits and see if what happens.