The signifier is the pointing finger, the word, the sound-image.
A word is simply a jumble of letters. The pointing finger is not the star. It is in the interpretation of the signifier that meaning is created.
The signified is the concept, the meaning, the thing indicated by the signifier. It need not be a 'real object' but is some referent to which the signifier refers.
The thing signified is created in the perceiver and is internal to them. Whilst we share concepts, we do so via signifiers.
Whilst the signifier is more stable, the signified varies between people and contexts.
The signified does stabilize with habit, as the signifier cues thoughts and images.