Hello Simran,

You can join Indian Army but, for girls there are only a few posts that you can enroll in. They are

SGD (Soldier general duty) which is women military police force is a category you will be eligible for after matriculation (10th level education)

Military nurse after you complete your 12th level education

Or after your Bachelors degree you can apply through UPSC and for technical posts if your Bachelors degree fall under those.

Do look into each and see which one interests you. Hope this helps and Good luck.