Prohibition of alienation means a legal form of restriction to dispose of real estate, more precisely the obligation of the owner not to alienate the property for an agreed period of time (not to transfer the ownership right to another person). It is an easement that you can have registered against the property.
What are the easements on the property?
Easements belong to the rights in rem to another’s property and are intended to restrict the owner to a certain extent. The latter must then refrain from doing something, suffer something or do something. These include the prohibition of alienation and the prohibition of encumbrances that make the property unbuildable.

What does the prohibition of alienation mean for real estate?
The prohibition of alienation is mainly used in practice when financing the purchase of real estate. For an agreed period of time, the owner may not transfer ownership (by sale, gift, etc.) to someone else. Like the prohibition of encumbrance, the prohibition of alienation is also regulated in Section 1761 CC.