A verb is a word that expresses an action, an event, or a state of being about the subject. Many ASL verbs can be modulated to indicate the subject and the object in a sentence. These inflected verbs are called indicating verbs. An indicating verb contain the information about the subjet-object structure.
The following base verbs that you learn in ASL 101 are some examples that can be modulated to contain the information about the subject and the object.
ask, copy, give, help, look-at, show, pay, tell, ...
For example, the indicating verb you-give-hir is a single signed verb in a ASL sentence [t]book[t] you-give-hir. The English translation is as follows: You give him/her the book.
If you change the movement in the opposite direction as above, the subject and the object are changed. That is, "S/he gives you the book."
This ASL verb help is a regular or base verb. It can be inflected within the subject-action-object structure.
This verb help is modified in direction, in which the signer moves from herself (the subject/pronoun "I") toward you (the object/pronoun "you"), that is "I help you."
Changing the direction results in a different subject-object structure. It indicates you-help-me.
The direction of this movement indicates help him/her. The locative in the right space refers to "her/him/it". The pronoun in ASL has no gender identity; it is neutral.
Not all verbs can be inflected. Below is a list of some ASL verbs that cannot be inflected. They are called plain verbs.
understand, know, ...
Now can you guess what it means? It's a crude equivalency to "I give you and you give me" or "we give each other".
In other word, the ASL word specifically means to-trade, to-exchange, or to give each other. It's called a reciprocal verb.
The ASL verb to-give can be inflected within a subject-action-object structure by changing a direction. The movement of this regular word to-give is not a directional verb.
The to-give is modified by directionality, in which the signer uses the same handshape of the verb to-give and moves from the herself (the subject/pronoun) toward you (the object/pronoun), that is "I give you." The indexing and the directionality are two of the modifiers in this sentence.
Changing the direction transforms from "I give it to you" to "you give it to me".
The signer says to the person B, "I give her/him" or "I give it to him/her". The handshape to-giveremains the same. The origin of the location is 'I' or 'me' (pronoun/indexing), the movement and direction indicate to-give, and the destination of the location refers to 'her/him/it' (pronoun/indexing).
Inversely, the opposite direction results in the sentence: "She/he gives it to me."
The signer, talking to the person B, says, "you give to him/her."
Also see indicating verbs
Related post: Verb inflection: HELP