YOU have the right to receive a full explanation of evaluations, assessments, supports, and services being offered, and/or any changes planned for your child, in your language or in your mode of communication, unless it is clearly not possible to give you the explanation in your language, before you give consent.
There are lots of listed commas in this sentence, but its pretty straightforward. Essentially, you have the right to have everything explained until you understand and before you are asked to consent. This also puts some of the responsibility back on the parent. If you don't understand the results of an evaluation, ASK before you consent. If you don't understand why services for your child are being changed, ASK before you consent. If English is not your preferred method of communication, you have the right to have a translator present. It can be one of your choosing or not, but you have to ASK. You are the parent (or guardian). Think of a doctor- you wouldn't consent to a test, medication, or hospital stay that you didn't understand. Its the same with services.
As a reminder, the full procedural safeguards are located here.