It is involved in assessing the syntax and structure of speech while listening. Speech is transported from the auditory area to Wernicke's area for evaluation of the significance of content words, then to Broca's area for analysis of syntax. People suffering from damage to this area (called Broca's aphasia, expressive aphasia, motor aphasia, or nonfluent aphasia) are unable to understand or create grammatically complex sentences; their speech will contain almost nothing but content words.
In speech production, content words are selected in Wernicke's area, grammatical refinements are added in Broca's area, and then the information is sent to the motor cortex.
The area is named after Paul Pierre Broca, who first described it in 1861, having observed the effects of damage and conducted a post mortem examination.