ばかり is used to say “nothing but”. It is typically used in conversation rather than formal writing.

【Noun】ばかり

ばかり has a negative connotation when used in this way. For example, a guy walking into a bar with the hope of meetings girls and being confronted with a room full of men might say to his friend:

男ばかりだよな。
Full of guys, eh.

Now, he could say:

男だけだよな。
Just guys, eh.

But だけ is very neutral and so the former sentence is arguably more natural given the context.

うちの息子はコンピューターゲームばかりやっています。
My son does nothing but play computer games.

ばかり is used to suggest that out of many possible options only one has been chosen.

うちの息子はカレーばかり食べている。
My son is eats nothing but curry.

Out of all the possible things he could eat, he eats only curry.

うちの息子はご飯ばかり食べている。(✘)
My son eats nothing but food.

Admittedly, this sounds strange in English as well, but just to drive the point home the sentence is unnatural in Japanese because you can only eat food—there is no other reasonable alternative.

If we want to say that he does nothing but eat we need to use ばかり with a different structure.

【Verb: te Form】ばかり いる
うちの息子は食べてばかりいる。
My son does nothing but eat.
この二人はいつもけんかしてばかりいる。
These two are always arguing.
最近ほぼ一日中寝てばかりいます。
Recently I’ve been spending almost all day in bed.

Using the possessive particle after ばかり instead of the verb to exist we can modify a noun.

【Verb: te Form】ばかりの【Noun】
遊んでばかりの夏休みを過ごす。
Spend the summer holiday just playing around.
学校をサボってばかりの学生。
A student who is always skipping school.

A bridging っ is often inserted in conversation.

嘘ばっかりだよ。
Nothing but lies.

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