What is the significance and usage of persona?

Persona is used by the poet to represent a character of his choice or to express his thoughts through a character.

What is a persona?

Persona means the character of a play or a voice of the poetry. The word is derived from Latin where it originally referred to a theatrical mask.  A persona can also be defined as the voice chosen by the author to tell a story or to define the speaker in a poem. A persona can be a writer himself, or it can be a fictional character which the author chooses as his mouthpiece.

Since Persona (Plural: Personae) is the voice of the author himself or the character used in that poem. If a poet uses a flattening and lucid language in his poem and not using any harsh or repulsive language, the persona in the poem can be deduced as "the poet must be a good guy."  Since that is what that particular poet portrays himself.