So then, if your entire body becomes filled with light, not having any part in darkness, then it will be entirely light, and, like a shining lamp, it will illuminate you.
Other versions
King James Version
If thy whole body therefore be full of light, having no part dark, the whole shall be full of light, as when the bright shining of a candle doth give thee light. English Standard Version
If then your whole body is full of light, having no part dark, it will be wholly bright, as when a lamp with its rays gives you light."New International Version
Therefore, if your whole body is full of light, and no part of it dark, it will be completely lighted, as when the light of a lamp shines on you."