What's the deal with temperature? I've watched a couple lectures now and it seems like whoever you ask you get a different answer. Isn't it always relatable to pressure of a gas in a closed system, and if so, what is all this noise:

The kelvin is now defined by fixing the numerical value of the Boltzmann constant k to 1.380 649×10−23 J⋅K−1. This unit is equal to kg⋅m2⋅s−2⋅K−1, where the kilogram, metre and second are defined in terms of the Planck constant, the speed of light, and the duration of the caesium-133 ground-state hyperfine transition respectively.
They're just fucking around, aren't they?

I think I kind of get the gist of enthalpy and entropy, but i have no idea what temperature is.