The atomic number of sulfur is 16, which indicates that a sulfur atom contains

The atomic number of an element indicates only how many protons are in that specific element. The atomic number of sulfur is 16, so it means that in one sulfur atom, there are 16 protons. The number of protons is also equal to the number of electrons in any given atom, so this number also indicates that there are 16 electrons in a sulfur atom.