The letter Alif in Arabic words plays several roles. It could be a chair or perch for hamza (qatee or wasly), it could be one of the three long vowel letters, it could also be an indication that something is dual, such as in the word ‘two books’, as a particle for a question or as a pronoun at the beginning of a present tense verb to mean ‘I’.
The pronunciation of this Alif with fatha, kasrah or dhamma vowels is also important in relaying the correct meaning and intent. One slight deviation in pronunciation and you might end up with a different word or a meaningless utterance.
أسمائكم – in the word ‘your names’, it is acting as a perch for hamza, at the begging of the word.
غضبان – in the word ‘angry’ it is a long vowel.
كتابان – in the word two books the last/second ‘Alif’ represents dual/two.
أبيتك هذا؟ – In the question ‘is this your house’ it stands for the question word ‘is’
أذهب – In the present tense verb ‘I am going it stands for the personal pronoun ‘I’
It also has other uses such as in imperative verbs or as ‘alif wiqayah’ (the protective alif) etc.
Be sure to now which Alif you are dealing with, as it can play several roles and have different meanings.