This is the 224th most frequent Japanese word.
ばかり
"ばかり" means "only," "just," "about to," or "nothing but," depending on context.
Here, 'ばかり' is used to indicate the exclusivity of the activity, emphasizing that the subject is doing only that specific action.
彼は朝からゲームばかりしている。
He has been playing only games since morning.
'ばかり' emphasizes the frequency or prevalence of the action, suggesting that the action occurs nearly all the time.
彼女は文句ばかり言っている。
She is always complaining.
In this instance, 'ばかり' is combined with the verb stem to indicate an action that has just been completed, highlighting recency.