5 months and child talking and understanding? NOPE. NO NO NO. Sorry, but that is not happening. sounds like demon baby from some movie. NO, not saying she has a demon baby. Just saying it is likely not happening.
dealt with many children in my career where parents say kids are doing things and they really are not. Had more than a few state the child was walking around and talking at 5-12 months and never once saw it happen. She is seeing what she wants to see.