Even though the universe is infinite we are trapped in to small pocket of it. That is called Visible Universe.
This consists of all the galaxies and other matters that can be observed from the Earth at the present time.
This is mainly because light and other signals from these objects have had time to reach Earth since the beginning of the cosmological expansion. Watch this video to find out more.
The observable universe is the volume of space that we can observe from Earth today. Light and other signals from galaxies and other objects within the volume has had sufficient time to reach us since the universe began expanding at the Big Bang . The limit of the observable universe is a horizon that we can not see beyond, since no signals from there has reached here yet.
Under the assumption that the universe is isotropic , which fits well with what we see, so is the radius of the observable universe is the same in all directions, which means that the observable universe is a sphere centered at the observer. This is true regardless of what shape the universe as a whole, and regardless of whether the universe is finite or infinite, but it is larger than the observable volume. Every place in the universe has its own observable universe which may, but need not, overlap with ours.
How (or if) space continues beyond our observable universe horizon, we can basically do not have any direct knowledge. So far as we have observed, however, we see the universe basically the same everywhere. No evidence suggests that space would have an end.
Age of the Universe is about 13.75 billion years, so one would think that the observable universe has a radius of 13.75 billion light years. However, this is wrong, because it does not take into account that the universe is expanding. The light reaching us today from the most distant objects, sent out when they were much closer than 13.75 billion light years; while light traveling towards us has become longer distance. At the same time the object from which light is emitted drifted away from us because of the expansion.
The diameter of the observable universe is estimated to be about 93 to 94 billion light years, which means that the distance to its boundary is 46-47 billion light years.