Cisgender means the person has a gender identity that matches the sex they were assigned at birth.
If you are a man and you were assigned male at birth, you are cis.
If you are a man and you were assigned female at birth, you are trans.
Non-binary can mean anything from not having a strong specifically male or female identity to closer to switching identities (bi-gender falls closer into this) to just having a lot of serious fluidity, but typically speaking at least part of the time the identity doesn’t match the assigned sex at birth.
There are some funky federation issues right now, the servers are straining a little bit under the load spike. I can see your post.