How does language convey the mood of the text?

Language helps set the mood 
Mood is what the reader feels while reading a scene or story. It’s not the reader’s emotions, but the atmosphere (the vibe) of a scene or story. It’s what the reader reads or feels or notices. Not all readers would necessarily report the same mood from a scene, although the writer does hope to achieve a particular feel common to every reader.

Language helps set the time that things are being side so that shows how the characters feel about something or someone