Welcome to the RC hobby! Its a blast and i hope you have a great time!I'm assuming this is a 3s battery and you could probably get a flight time of around 10-15 minutes if you fly conservatively.The best way I've found to get a real estimate is to fly an airplane for about 5 minutes then land it and check the capacity and then do the math with that statistic. Generally you only want to go down to about 30 percent battery capacity. to check the capacity of your batteries i would recommend getting a battery checker similar to this one -https://www.amazon.com/gp/product/B01JOO3H5M/?tag=lstir-20
it really depends upon the motor, the prop, and the flying style that you do.
a 1806 motor on a 3S-850 can last for almost 20 mins with the correct prop (6x30) if flying reasonably. if going full throttle the whole time chop that in half, which is still a long time. most RC flights range from 3 - 6 mins unless flying a glider. if you get more than that you are doing great.