Pluralization is a process of making a plural of a signed word. In English, a speaker adds "s" to a noun word for plural. The word cat is a singular and cats is a plural.
In sign language, there are different ways of expressing plurals: regular ASL words, handshape, movement, numeral incorporation, and reduplication. A signed word can be modified by a handshape, a movement, a direction, and/or a repetition to signify a degree of plural.
It is important to remember that these parameters are not necessarily applicable to all signed words. Some may work, some will not suit well. In English, fish is also a plural, not "fishes". There are rules and exceptions in every language.
One of the ways of pluralization is the regular words in ASL, such as several, many, lots, few, etc. The singular word many can even become a plural in ASL. Eg. many, many (see duplication for explanation).
[L] The "book" sign is a noun or referent. After signing the book now as a referent, the modified sign shows [R] lots of books on shelf. The right-handed claw (a classifier) and the deep facial expression describe "lots, lots", "unbelievably many" and similar versions.
[L] The "book" sign is a noun or referent. [R] After signing the book established as a referent, the handshape is a classifier to represent the book, moving from left to right. This movement is a form of pluralization. It means a set of books on the shelves.
'She' and 'he' are a singular. [L] The Signer points with her index finger for s/he/it, which is a neutral gender. [R] On the other hand, the Signer sweeps across for they, them, which is the plural sign.
In numeral incorporation, a ASL number is incorporated with a signed word. Not all words can be incorporated with numbers. Here are a few examples below.
It is a regular ASL word for day.
Rather than signing two ASL words seven and day separately, numeral incorporation is used in one inflected ASL word seven-day for "seven days".
Some classifiers can be pluralized. For example, [L] the upright 1-handshape classifier can represent a standing person, pen, stick or another. By changing this handshape to "2" or "V", this classifier then can represent two persons (standing), two sticks (horizontal orientation), and so on.
Reduplication is another way of pluralization.
For example, inflecting or modulating a regular verb [L] fly (plane), the signer uses both hands alternating few times, which means, [R] fly frequently, fly many times, or several busy flights.
Based on the [L] regular sign-word find, the Signer reduplicates it, which becomes a plural. Inflecting or modulating this regular sign-word [L] find, the Signer uses both hands alternating few times, which now means [R] find out more and more or discover many things.