If you see TM after a name of a product, does the TM protect just the name or the entire product?

I believe a trademark can apply to a single product or a product line. It all depends on the type of trademark the person or company applied for.

From Wikipedia:

A trademark or trade mark (represented by the symbol ™)[1] or mark is a distinctive sign or indicator of some kind which is used by an individual, business organization or other legal entity to identify uniquely the source of its products and/or services to consumers, and to distinguish its products or services from those of other entities. A trademark is a type of intellectual property, and typically a name, word, phrase, logo, symbol, design, image, or a combination of these elements.[2]