Breastfeeding and pregnant?

So I keep getting mixed info from different health professionals, I’ve had some tell me that you can breastfeed while pregnant and even after as your breast have this way of indicating what each child needs (or they said something like that which is confusing me) and I’ve had some turn to me and say I didn’t think you couldn’t breast feed while pregnant. So I wanna know what others have been told and if they managed it during pregnancy.