What is a sentence using the word Indecipherable?

Answer 1

I find most doctors' handwriting indecipherable.

It means you can't read someone's handwriting. That is their handwriting is so scrawly or something that you can't see what it says, rather than you can't read. I.e. their handwriting is illegible.

Answer 2

The ancient manuscript was indecipherable, with its faded and worn text proving to be a mystery to all who attempted to read it.