Deliberate exaggeration, which no one takes literally, to give emphasis to a feeling or a situation.
In Hamlet
It will be short. The interim is mine, / And a man's life's no more than to say 'one.'
To say that a man’s life “lasts no longer than it takes to say ‘one’” exaggerates how brief it is, without anyone taking the phrase literally. The exaggeration shows Hamlet seeing time as short and the “interval” as his.