The asset deal is the alternative to a share deal* when buying or selling a company. In this case, it is not shares in the company that are transferred but the assets belonging to the company by way of acquisition of all or certain assets.
An asset deal is particularly suitable if only certain assets of the company are to be sold. An asset deal can be problematic if the company wants to acquire customer data or in relation to employees who belong to a particular line of business.
*Find the definition here: share deal