Class 35 is for retail and marketplace services; businesses that sell products made by other brands, or that provide business administration and management services.
If you sell only your own branded products, Class 35 is not required. Your product-specific class (Class 25 for clothing, Class 21 for kitchenware, and so on) covers the goods and your brand's use in connection with them.
Class 35 becomes relevant when you operate a marketplace or store that sells multiple brands' products, when you provide business services to third parties, or when you run a physical or online retail operation in which the retail service itself (as distinct from the goods sold) is a significant part of the business identity.