From Second Life Wiki
A ban can also refer to a permanent termination of a (Teen) Second Life account (which can only be done by Linden Lab and might be a consequence of Terms of Service and/or Community Standards violation).
The list of those banned from an area, by use of a script, or by Landban that otherwise allows visitors.
Lines of floating red letters spelling out “no entry” that appears on the boundaries of a land parcel that your avatar is not allowed to enter. Ban lines are limited to a height of 768 m above the terrain mesh when you're explicitly banned from the land. If the parcel is simply not pubic access or restricted to certain Residents/groups, then the lines go up to 50 m above the terrain mesh.
Teleport Rules for Banned Avatars
Teleporting to a parcel from which you are banned (either explicitly or because the parcel is not public) will send you to the closest spot in the region you're allowed to access. Teleporting to a region from which you are banned (either explicitly or because the estate is not public) will fail, with the error message "You are banned from the region."