Some classifiers function similar to pronouns, in which a classifier can represent a group of nouns. A few examples of common semantic classifiers are CL:1 (person, etc), CL:3 (vehicles), CL:2-bent (sitting animal/people, chair, etc).
For example, the horizontal "3" handshape (above image) of a classifier can represent a particular group of nouns, such as a car, a motocycle, a van, a submarine, a bicycle, etc. It is analagous to the English word vehicle but this English word is a noun. The ASL classifier is a "pronoun". Like pronouns, a referent (noun) must be signed before a classifier can be applied to.
This upright "1" handshape of the classifier can be used to represent an object or a person. An object is usually thin and/or tall object (eg. twig, pole, pen, etc.).
A particular noun is first signed before its classifier can be used to represent its referent in its place. For example, the signer sign 'woman' and then uses this classifier repeatedly as a pronoun in the sentences.
More classifiers and examples
The classifier "V" or "2" generally represents two persons standing or walking (if moving this classifier) together. It's also known as a plural classifier.
The CL-2 can represent a standing person, a person lying down, etc. Whereas, the bent CL-2 can mean a kneeling person, a sitting person, beaver's teeth, etc..