To be on good terms; to have a close or friendly relationship with someone.
あの二人は学生時代から仲がいい。
Those two have been close since their school days.
職場で仲がいい同僚とはランチによく行く。
I often go to lunch with coworkers I'm close to.
家族が仲がいいと、家の雰囲気が明るくなる。
When a family gets along well, the atmosphere at home becomes brighter.
彼女とは趣味が合って仲がいいが、仕事ではライバルだ。
She's someone I get along with because we share hobbies, but we're rivals at work.