When you’re desperately trying to keep the conversation going but really can’t, the other person will notice it and it will be awkward.
Find a common ground or something you’d be interested to hear. It can be as simple as asking someone what their occupation is or hobbies are or did you see the game/event yesterday.
Just let the other person talk and listen. If you can contribute to the conversation: go ahead, that’s great. If you feel like you should say something, but there’s nothing to say: just continue listening and let them know you are actively listening. Be like: ohh, really? How’d that go?, uhuh, oh wow! They’ll ask you questions if they feel you should’ve said something.
Is the conversation on a dead end: wrap it up. It’s okay. The more comfortable you get around a person the easier it will be to talk to them the next time.