Okay, so in the case of a wikipedia article, if you're really ignorant of the symbology used and don't know where to start, just click 'edit' and look at the latex code. If that's not helpful, like the case where the latex for the P(.) function is simply 'P', read the contextual information.

"The posterior distribution can be defined by marginalizing over joint distribution, factorized into its independent prior distributions and then dividing by the partition function."... or whatever.

If the article doesn't have any contextual info, then you probably shouldn't rely on it if you're learning. Look somewhere else.

> It's like reading source code without comments or named variables or indentation of any kind

Math is an abstraction. It is more abstract that most code, that is why implementing math into code is something people make a living doing. How would you prefer that math equation you gave be presented? As the (currently) top comment states, those symbols are FULL of meaning. Understanding what that equation means is more than just knowing that "P stand for probability, and the funny angled thing is a sigma and that means sum." In fact, quite often an equation represents an idea that is simple enough to conceptualize, but extremely non-trivial to bring into more concrete terms. For example, that equation you posted looks like the kind of thing you'd see in a paper using Bayesian methods. In many cases to implement that equation would require Markov chain monte carlo sampling, maybe a gradient descent algorithm, a quadratic program solver, who knows. It's an infeasible way to present the ideas, at best.