noun
General sense: a person who follows a leader, movement, or ideology. Less common than the social media sense in modern Japanese.
彼はカリスマ的なリーダーで、多くのフォロワーがいる。
He is a charismatic leader and has many followers.
Specifically refers to a follower on social media platforms such as Twitter, Instagram, etc. This is the most common usage in contemporary Japanese.
インスタグラムのフォロワーが1万人を超えた。
My Instagram followers exceeded 10,000.
フォロワーを増やすために、毎日投稿している。
I post every day to increase my followers.