You need to have their phone number to track your friend or any known person through your phone. Ensure that the person you are finding must have an android phone. You need to go to the google map app of your android phone and then look for the 'find my device' option in the search box. By clicking on this option, you will be directed to the person's current location, and you will get some additional information about the past locations of the person. Pertinent to note, you can't execute mobile tracking with Google Maps without the concerned person's prior permission.