You need 326 seats to form a government and pass legislation, the Tories aren't going to hit that number so they're going to have to make deals with other parties to get enough votes to pass bills.
Up in the air what effect that will have on Brexit but it will most likely mean a more "soft" Brexit.
Basically we're going to have a weak and wobbly coalition of chaos lead by May or maybe someone else after she resigns, who knows!