这个英语句子是从句吗?主句是什么?从句是什么?brick-and-mortar is a traditional "street-side" business that deals with its customers face to face in an office or store that the business owns or rents

是定语从句
brick-and-mortar is a traditional "street-side" business 是主句
deals with its customers face to face in an office or store that the business owns or rents是从句，用来修饰"street-side" business。
这句从句中的that the business owns or rents是定语从句，修饰store，
所以这句话是定语从句中套定语从句

一个主句,两个定语从句.
主句是brick-and-mortar is a traditional "street-side" business
从句 that deals with its customers face to face in an office or store 修饰business,
从句 that the business owns or rents 修饰office or store