Numeral incorporation is a morphological process, in which a number is incorporated into a handshape, a classifier, or a pronoun of a sign.
Let's look at an example of two+day and two-day. Notice the difference between these two glosses? The former has a plus symbol which means two ASL signs and the latter has a minus symbol which means one sign (despite two English words for the sake of glossing).
The sign two+day has two separate signs (two morphemes): TWO and DAY.
Numeral incorporation occurs when one incorporates a number into the sign DAY. It becomes one sign, but it has two meaningful parts (morphemes). The numeral part is a "bound morpheme."
The ASL word hour is a regular noun as shown above.
The sign HOUR can be incorporated into a number from one through nine. Beyond ten, one has to sign two separate signs NUMBER and HOUR.
As a basic rule, numeral incorporation can only work up to 9 numbers. Beyond number 10, use the regular separate signs such as 12+MONTH.
Numeral incorporation can work with the following ASL signs from one through nine (from one through five in a few categories): MINUTE, HOUR, DAY, WEEK, MONTH, O'CLOCK, and so on.
[L] the upright 1-handshape classifier may 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.
The images above illustrate ASL pronouns you and I/me respectively, which can be interpreted as you and me/I. They can be incorporated with a manual number as shown below.
Instead of signing you me/I, the signer can incorporate the manual number two into the handshape to create a V- or 2-handshape. It means the same as "you and me/I", "both of us", or "the two of us".
Related topic: The Rule of 9