Hello!
In the professional field, using informal language can make you seem less sophisticated, which could damage your professional reputation. You will not to well in meetings or interviews if you are seen like that. Your boss will want to have sophisticated and trustworthy employees, so you will want to seem that way through the language you use.
In your personal life, using informal language will not go against you in the long run. You could tell a teammate in a sports game, "Kay, you gonna meet me o'er there?", and it will not affect the way you are seen in the professional word. You can get your point across quickly in your personal life without being judged.
Hope this helped!
