Comment I posted yesterday was removed due to lack of citations, so here it is again with some supporting sources at the end.
When "asset freezing" is used by State A as a sanction against foreign nationals/parties belonging to State B, in a practical sense it typically means that State A will freeze any and all assets under its jurisdiction (i.e. funds deposited in an account in a bank owned by State A) belonging to the nationals/parties in question from State B. "Asset freezes" also usually include outlawing any entities from State A from doing any business with the foreign entities in question. "Asset freezing" as an international sanction does not go as far as to freeze assets held in the foreign entities' home country (or any other country not participating in pressing the sanctions).
For example, when the US says it will be freezing the assets of a group of individual Venezuelan officials, it doesn't mean that the US will be able to freeze the money that they hold in Venezuelan banks or foreclose on their house in Venezuela. Rather, it means that they will freeze any money held in US banks, investments in US companies, etc. and outlaw US entities from engaging in any sort of business with them. The overall point is that such sanctions are only effective if the entities at the receiving end happened to have a lot of assets tied up in US firms at the time the sanction came along.
On the 2011 US freeze of Libyan assets
On the new US sanctions against Venezuelan officials
On EU restrictive measures (including asset freezes) against foreign entities
On multilateral asset freezing as used by the United Nations Security Council