This means an action has just been completed very recently. It's often used when the recency of the action is important, or when something is still new from that action. Attaches to Vた form. Example: 彼は日本に来たばかりです (He has just come to Japan).

ある動作が「終わったばかりだ」という状態を表します。Vた形に続きます。「Vたところだ」と似ていますが、その状態が続くニュアンスも。