A woman named Harry Miller comes before a judge and I pretrial hearing. she's charged with stealing thousands of dollars. she pleads guilty. under the sixth amendment what is her right?

The Sixth Amendment guarantees a defendant the right to a speedy public trial but re-read your question, she has pled guilty, so her rights now will include facing the penalty for her crime since she gave up her right to a trail with a guilty plea.

She has the right to a speedy trial.