It would be dialect.
Dialect is the particular sounds, grammar, and/or spelling to distinguish a certain type of person or group from another.
Basically, it is the way people talk (their accents)
For example,
There is the southern - "Hey y'all!"
Brooklyn - "Hows ya doin?"
British - "'Ello"
Australian - "'Ay, mate"
This also refers to grammar and spelling. Like in your question "You a lie". Normally we would say "You are lying" or "That is a lie", but the particular person, based on their culture, ethnicity, etc. will speak differently.
Hope this helps!
I hope
