A claim or obligation registered against a property.
Two common types of encumbrance are a lien (a claim for money owing) and an easement (the right of another party to enter your property).
When you are buying a property, your lawyer will inform you of all encumbrances on the property, and you will have to decide how to proceed with each one.
You may choose to accept the encumbrance as-is, or you may wish to change your offer in some way so that you are compensated for the encumbrance. (The specific remedy is a matter to be decided between the Buyer and the Seller.)