“Knows her own mind” means that she has a strong and clear sense of what she wants; of right and wrong; etc. Being practical is different; a person could be practical and yet not “know their own mind,” and vice-versa.

"knows her own mind" cuz the woman want to be understanding with you. about like, food, etc

When you say that someone knows their own mind, you are saying that they will not be persuaded to do things they don’t want to do. For example: A parent discussing the safety of their daughter Susan, when she leaves home, might may say “you don’t have to worry about Susan she knows her own mind”. Another example: a parent discussing that their child could be persuaded to do bad things might say “I know he’ll be ok because he knows his own mind” The use of practical in your example is a second and separate descriptor.

A practical woman who "knows her own mind" means that she is a woman who makes her decisions based on what she thinks is sensible. She "knows her own mind" means she knows herself well, she is confident and makes choices based on who she knows herself to be as a person. I hope that makes sense to you.