The clause: that have simple, easy to understand alternativ

[NewHope]

Context:
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?

[Francois]

It means don't use buzzwords if they have simpler and clearer alternatives. The part you put in boldface is applies to 'impressive-sounding nonsense words'.

In addition, I think the author used "simple, easy to understand" as an adjective to modify "alternatives". Right?

Yes.

FRC

[NewHope]

BTW, do you mind telling whether your screen name is derived from The Call of The Wild by Jack London?