You are looking at the deepest view of space that humans had managed to obtain up to the time of this article: an image containing roughly 10,000 galaxies.
As part of a project called the Frontier Fields Program, the Hubble Space Telescope, operated by NASA and ESA, imaged a collection of about 7,000 bright galaxies gathered in the enormous cluster known as Abell 2744. More importantly, by using the gravity of this galaxy cluster as a giant natural magnifying glass, Hubble was also able to detect the extremely faint light of nearly 3,000 galaxies lying behind it.
The galaxies behind the cluster are as far as 12 billion light-years from us, whereas the cluster itself is roughly 4 billion light-years away. This means that we are seeing these distant objects, albeit not very clearly, as they appeared about 12 billion years ago—on a cosmic timescale, relatively soon after the creation of the universe following the Big Bang.
As illustrated in the lower-right corner of the accompanying image, the immense gravity of Abell 2744—also known as Pandora's Cluster—warps the fabric of space around it. As a result, the extremely faint light from galaxies hidden behind the cluster, and far more distant from us than the cluster itself, is collected, magnified and brightened like light passing through a lens, allowing it to reach us.
The original article states that without Pandora's Cluster, the enormous distance between us and these remote galaxies would make imaging them impossible even with the most powerful future generations of space telescopes.
More information and images are available through the original Hubble website link preserved below.