If you happen to win, you'll get back carrying a few alien bodies and their artifacts. Your scientists will try to replicate these items. Research will often take many long days. Once you build a containment chamber, you'll be able to bring back wounded or captured aliens and interrogate them. With time, better weapons, including alien technology, will become available. But so will the threats that face you. At first, you'll fight the scouts. Later on, you will face the invasion forces.