Look back times of approximately 13 billion years.
A brief excerpt about this photo from HubbleSite:
“This is the deepest image of the universe ever taken in near-infrared light by NASA’s Hubble Space Telescope. The faintest and reddest objects (left inset) in the image are galaxies that correspond to “look-back times” of approximately 12.9 billion years to 13.1 billion years ago. No galaxies have been seen before at such early epochs. These galaxies are much smaller than the Milky Way galaxy and have populations of stars that are intrinsically very blue. This may indicate the galaxies are so primordial that they are deficient in heavier elements, and as a result, are quite free of the dust that reddens light through scattering.”
When they mention “look-back times”, they are talking about how long it takes for the light from those stars to reach us. So the light left those stars 13 billion years ago and we’re just seeing it now.
Read the full details and check out the image for yourself at HubbleSite.