Clippityclop any animal with front teeth is forbidden and the animal must chew its cud. No rodents, scavengers, pigs or predators Also the animal should be slaughtered according to the bible.
Fish must have fins and scales. No catfish, shrimp, or lobster.
Jews do not eat the fat of any animal and certain parts of the animal if it is allowed are also forbidden.
You can buy foods if there is a local grocery that sells Kosher meats. They are more expensive than non kosher foods.
She might not eat dairy and meats at the same time and she cannot use the same plate for meat and then for cheese.
however if she is allowed to eat at your house she probably does not adhere strictly to a kosher diet.
Talk to the mother and show her you will abide by the dietary restrictions so your young guest may enjoy her visit and your family experience another culture.
Glad you asked and if you have any other questions ask me. Shalom