It's a pronoun used to refer to a male person who is the subject or object of a sentence.
Here are some examples:
* 他很高。 (Tā hěn gāo.) He is tall.
* 我看到他了。 (Wǒ kàn dào tā le.) I saw him.
It's important to remember that "ta" (他) is used for male individuals. For female individuals, you would use "tā" (她).