As I understand it, this is what the scientists think right now....operative words "right now".
It was once thought that the universe began about 14 billion years ago due in large measure to us being unable to detect anything older than 14 billion years.
We look out and beyond that frontier there was but a void.
But then it was realized that galaxy A is "moving" (see above about space expanding) away from us at, say, 1/4 the speed of light and galaxy B is moving away from us at, say, 99/100 the speed of light.
But what about galaxy C. Well, it's moving away from us at the speed of light plus; therefore it's light will never get back to us to observe.
But more baffling (to me, anyway), if there were another astronomer right on the edge of our known universe....
He would be able to see 14 billion years out...meaning we would be right on the edge of his know universe.
But if there was an astronomer on the edge of his universe...same thing.
Therefore, you could just keep going....in all directions.....forever.