Is it within our rules of modesty for a girl age 12 or more to play ice hockey? If she joins a girls team but coach is male. Im asking bc they are wearing all the hockey gear and helmet.

There is no harm itself playing Hockey as long as a woman secure her modesty and her coach is not touching her during the training. As long as 12 years girl concern as she has already reached to her age of bulugh (puberty) according to Islamic Shariya therefore all rules of hijab and modesty will be applied for her too.