Erlang the language is pretty simple. What takes some grokking is first, the concurrency approach; and second, the OTP library. If you're used to Golang or using Python with threads communicating through Queues, Erlang works about the same way, with the additional feature that a process exiting also kills its parent unless the parent explicitly traps the exit signal. In OTP parlance, a process that traps exit is called a supervisor, since its usual function is to restart the crashed process.

Learn You Some Erlang has some useful discussion of OTP, and it was a big help to me to read through the OTP library source code. That of course will also get you more comfortable with Erlang itself.