The clause: that have simple, easy to understand alternativ
Remember, your writing should be interesting but also easy to read and understand. Does this mean you should avoid technical language? No. You may need to use technical terms, but avoid impressive-sounding nonsense words that have simple, easy to understand alternatives.
Does the clause meant "It is technical terms that have simple, easy to understand alternatives"?
In addition, I think the author used "simple, easy to understand" as an adjective to modify "alternatives". Right?