A predicate noun is a noun connected to the subject of the sentence by a linking verb. A linking verb is a verb that connects words that are the equivalent of each other. In other words, the subject is linked to another noun, the predicate noun, by means of the linking verb. It can help to use an equal sign (=) to visualize the connection between the predicate noun and the subject. 

• Ryan was a banker. (Ryan=banker. Was is the linking verb.)

Study the following examples and try to identify the predicate nouns and the linking verbs. The first sentence is explained for you.

• Sheila is president of the company. (Linking verb: is. Predicate noun: president. Sheila = president)
• This park is the best spot to relax in the entire city. 
• The restaurant became a popular destination.
• They are professors.