Is the word a a pronoun?

No, the Word "a" is an indefinite article, a Word placed before a noun to indicate that the noun is a general one of its kind.

There are two indefinite articles:

• the article "a" is used before a Word that begins with a consonant sound;
• the article "an" is used before a Word that begins with a vowel sound.

The Word "the" is the definite article, a Word placed before a noun to indicate that the noun is a specific one of its kind.

A pronoun is a Word that takes the place of a noun in a sentence.

Examples:

We need a flashlight. (any flashlight will do)

The flashlight is in the second drawer. (a specific flashlight, a specific drawer)

I found it. (the pronoun "it" takes the place of the noun "flashlight")