Is they a personal pronoun

Yes, the Word 'they' is a personal pronoun, the third person, plural form; a Word that takes the place of a plural noun or two or more nouns for people or things as the subject of a sentence or a clause. Examples:

The Browns will be joining us. They will be here at eight.

John and Jane will be joining us. They will be here at eight.

The corresponding objective, third person, plural, personal pronoun is 'them'.