Answer:
Conveys comfort after the unpleasant images of the previous stanza.
Step-by-step explanation:
In the first three stanzas, we can see that the narrator associates the blue bird inside him with bad and unpleasant situations. These situations are caused by the narrator so as not to let the blue bird not come out of the narrator's heart and be perceived by people, but the narration presents a series of adjectives that cause unpleasant images to the reader.
However, in the fourth stanza, the narrator presents a little comfort, releasing this bird a little and feeling a certain relief, peace and satisfaction that are transmitted to the reader and contrast with what was portrayed previously.