What are the four sentence moods and what do they signify?

Ultimately, you must not forget that the signification of all literary devices is dependent on their context. There is no standard connotation of any device.  1. The declarative sentence mood:  This mood occurs when a speaker makes a declaration or claim. It can be as simple as 'I will win the competition.' The declarative mood is often linked to the creation of an assertive tone, which could demonstrate self-confidence, or even a self-centered nature.  2. The interrogative sentence mood:  Questions are always examples of the interrogative sentence mood and vice versa. For example: 'Who is he?' The interrogative sentence mood can create an atmosphere of uncertainty, demonstrating a lack of confidence from the speaker's perspective. Equally, the interrogative sentence mood can be viewed as a speaker's attempt to undermine their peers by challenging them or 'putting them on the spot.' Consequently, analysing the interplay between interrogative and declarative sentence moods is revealing of the power balance between speakers.  3. The imperative sentence mood: Expressing a desire or wish, demands and requests are examples of the imperative sentence mood. For example: 'Answer me now!' Depending on the context, imperatives can create an authoritarian tone or a frantic atmosphere, particularly if imperatives are in abundance or not followed by a response. Imperatives can be linked to hierarchy: a powerful character will use imperatives, a subordinate character will listen to imperatives.  4. The exclamatory sentence mood: Just like an exclamation mark, the exclamatory sentence mood describes a strong emotion.