African American Vernacular English (AAVE) – without getting into its terminological complications – has a versatile and distinctive grammar for conveying aspect.* For one thing, it can omit the copula be in some situations: She is working today → She working today.
This is known as copula deletion, zero copula, or zero auxiliary. The American Heritage Dictionary says it’s “even more characteristic of AAVE than is invariant habitual be”. The latter, as in She be working, differs from zero copula in that it refers mainly to habitual or prolonged action.
The two constructions – zero copula and habitual/invariant be – are sometimes confused by people unfamiliar with AAVE’s syntactic subtleties, as the dictionary’s fifth edition reports:
In place of the inflected forms of be, such as is and are, used in Standard English, [AAVE] and some varieties of Southern American English may use zero copula, as in He working, or an invariant be, as in He be working, instead of the Standard English He is working. As an identifying feature of the vernacular of many African Americans, invariant be has been frequently seized on by writers and commentators trying to imitate or parody black speech. However, most imitators use it simply as a substitute for is, as in John be sitting in that chair now, without realizing that within AAVE, invariant be is used primarily for habitual or extended actions set in the present.
You can read more about the usages here, and via the previous link, both of which point to an earlier edition of the AHD.
The distinction gets a nice mention in George Pelecanos’s crime novel King Suckerman. Two characters, Rasheed and Cheek, are talking about the eponymous (fictional) blaxploitation film showing in their city:
“What new one?” said Rasheed.
“King Suckerman,” said Cheek.
Rasheed looked up. “That the one about the pimp?”
“Not any old pimp. The baddest player ever was. ‘The Man with the Master Plan Who Be Takin’ It to the Man.’”
“Who be. That’s what the ad says, huh? I bet some white man wrote that movie; produced it, too. Even wrote that line about ‘the Man’ that’s gonna get you in the theatre.”
King Suckerman hasn’t always been “takin’ it to the man” – at least not in a way worth making a film about – but he is doing so now. Who be takin’ it to the man indicates ongoing rebellion; who takin’ it to the man would imply more immediate (and hence cinematic) events. So we infer that whoever was responsible for the tagline is not a native AAVE speaker.
John Rickford says the invariant habitual be construction “has clear parallels with and possible derivations from creole ‘does be’”. Does be is a feature of Hiberno-English too. Merriam-Webster’s Concise Dictionary of English Usage summarises:
The ability of a verb form or auxiliary to indicate continuation or duration of an action is called by grammarians and linguists aspect. Since English is somewhat deficient in aspect, compared to some other languages, these dialectal forms [Black English and Hiberno-English] do constitute an enrichment of the language. But they are not yet available to the writer of ordinary standard English, and no one knows if they ever will be.
* Grammatical aspect is defined by Huddleston and Pullum as “a verbal category mainly indicating the speaker’s view of the temporal structure of the situation the clause describes, such as whether it is habitual or complete”. For more, see SIL and Glottopedia.