What is the function of a linking verb

Linking verbs are verbs that do not express actions, but conditions or states, such as all forms of the verb "to be," and the verbs "to become" and "to seem." Their function is to connect the subject of a sentence to a word that identifies or describe the subject. Take a look at the following examples:

William is excited about his promotion.

The linking verb "is" connects the subject "William" to the word or adjective "excited" which describes the subject.

The winter scene was mysterious.

The verb to be "was" links the subject "the winter scene" to a word that describes it: "mysterious."

She seems sad

The verb "seems" links the subject "see" to the adjective "sad."

she needs to add a conclusion summing up the entire essay along with an ending sentence to complete it all nicely.