N5
だけ
Only, Just
今夜は食べるだけ、何も飲まない。
Tonight I'm only going to eat, I won't drink anything.
Explanation
「だけ」 means 'only': it limits the range and leaves everything else out: 「千円だけある」 (I have only 1,000 yen). It is objective and neutral, with no complaint. It can follow nouns, amounts and verbs: 「見るだけ」 (just looking). 「が」 and 「を」 are replaced by 「だけ」; 「に」, 「で」 and 「から」 stay and 「だけ」 goes after them.
Mixed up with
「だけ」 vs 「しか〜ない」: 「千円だけある」 just states that there is 1,000 yen; 「千円しかない」 always takes a negative and carries regret: 'only 1,000 yen, it's not enough'.
「ばかり」 means 'nothing but' and often carries dissatisfaction: 「肉ばかり食べる」 (eat nothing but meat); 「肉だけ食べる」 just says meat is the only thing eaten.