In your case, try a search for "espsoftwareserial". I saw mention of it in another topic. (see below)
EspSoftwareSerial - Arduino Reference
I don't see why anyone thinks it's necessary - but anyway.
Like anything else, you should get familiar with it outside of your project and only then bring it into the mix.
This as opposed to the usual (around here): lick it, stick it, hope for the best, now I'm disappointed.