. My dad just recently bought 4 hens and a roo. One hen has laid one egg so far. But my dad said they don;t need an incubator, that the mother would keep them warm and feed them etc. is this true?
That depends on the breed of chicken you have AND whether or not she is "broody" at the time she lays the egg.
The short answer would be "No" she probably won't sit on the egg.
Most egg-laying chickens today are bred to lay eggs; they don't sit on the nest.
If you have a breed of chicken that is known to sit and hatch eggs (e.g., Silkies), then one day you might get a hen that will stop laying and just sit on the eggs.
If that happens, then you can put a few more eggs under her so she can hatch them.
I currently have one of my d'Uccle hens go broody and I put four Guinea eggs under her so she can hatch them.
If you do not have a hen that is broody, then you will need an incubator to hatch the eggs.
What kind(s) of chickens do you have?
Hens go broody when you don’t want them to… and won’t go broody when you do. 
