"Kind of" means "a little" or "somewhat". People often use it in spoken English:
It kind of took me by surprise.
You can use "kind of" before an adjective ("kind of shy") or before a verb ("kind of took me by surprise").
Another phrase with a similar meaning is "somewhat":
Most students find that university courses are somewhat more difficult than the classes that they took in high school.
"Somewhat" is more formal. Use "kind of" for most situations and "somewhat" when discussing academic topics or in writing.
The pronunciation of "kind of" sounds like "kinda".