What is the temperature of the black hole? Are black holes hot or cold? I was thinking because I wanted to know if there any human sustainable temperature so we can travel in it.
See Hawking radiation. The temperature of a black hole depends on its mass, and is given by: 

$T=\frac{hc^3}{16\pi^2GMk_B}$

Where $h$ is the Planck constant, $c$ is the speed of light, $G$ is Newton's gravitational constant, $M$ is the mass of the black hole, and $k_B$ is the Boltzmann constant.