As per Odoo Documentation, Data such as Products, Contacts, and Equipment can be shared or set to be shown for a specific company only. To do so, on their forms, choose between:

• A blank field: the record is shared within all companies.

• Adding a company: the record is visible to users logged in to that specific company.

You can set the company from product form, General information tab.

See more in the below link:

https://www.odoo.com/documentation/14.0/applications/general/users/companies.html#manage-companies-and-records