Just (だけ)
だけ is the most basic way of expressing “only” or “just”, e.g. I’ll just have one drink.
| ひとつだけ。 | 
| Just one. | 
| 私はビールを一杯だけ飲みます。 | 
| I’ll just have one drink. | 
The object particle is often omitted when だけ is used.
| 私はただのウエートレスだけじゃありません。 | 
| I’m not just a waitress. | 
だけ can also be added to verbs.
| カメラの操作は簡単です。ボタンを押すだけです。 | 
| The camera is easy to operate. Just push the button. | 
| 血を見るだけで気絶します。 | 
| Faint at just the sight of blood. | 
Nothing More Than (しか〜ない)
The particle しか is used with the negative to express that you have nothing more than that thing.
| チケットが二枚あります。 | 
| I have two tickets. | 
| チケットが二枚しかありません。 | 
| I only have two tickets. | 
| 10ドルがある。 | 
| I have $10. | 
| 10ドルしかない。 | 
| I have just $10. | 
The insinuation is that the amount you have ($10, two tickets, etc.) is not enough or not a lot. Consequently, there are situations where we cannot use しか〜ない.
| お願いがひとつしかありません。(✗) | 
| I have just one favour (to ask). | 
This is unnatural because the implication is that one favour is not enough—you should be asking for several things. In this case, we should use だけ.
| お願いがひとつだけあります。 | 
| I have just one favour (to ask). | 
しか can be appended to other particles.
| お金は担当者にしか払わない。 | 
| I will only pay the money to the person in charge. | 
Note the use of は to place emphasis on the money.
| お父さんとしか話しません。 | 
| I will only speak to my father. | 
None, Many, Several
Below we look at ways to express none, many, and several.
も〜ない
Of course we already know how to express “none” with the negative.
| 本がない。 | 
| I don’t have a book. | 
The structure も〜ない let’s us emphasise that we don’t even have one.
| 1ドルもない。 | 
| I don’t even have a dollar. | 
| 本が一冊もない。 | 
| I don’t even have one book. | 
| 私はビールを一杯も飲みません。 | 
| I won’t drink even one beer. | 
We can combine question words with も and a negative verb to create the pronouns anything, anywhere, nothing, etc.
| 何もない。 | 
| I have nothing. | 
| どこにも行かない。 | 
| I won’t go anywhere. | 
| 誰にも会わない。 | 
| I won’t meet anyone. | 
| 誰とも話さない。 | 
| I won’t speak to anyone. | 
| 何とも思わない。 | 
| I don’t care at all [I don’t think anything]. | 
も〜ある
Used with an affirmative verb the meaning is flipped, allowing us to emphasise that the quantity is a lot. It is the opposite of しか〜ない.
| 1億ドルもある。 | 
| I have as much as one-hundred million dollars. | 
| 数時間もかかると思うよ。 | 
| I think it will take as much as several hours. | 
| 彼女は1時間も話しましたよ。 | 
| She spoke for a whole hour. | 
何【counter】も〜ある
Effectively, this expression is saying that no matter what the number you have at least that many to give us “countless” or—more simply—”many”.
| 本が何冊もある。 | 
| I’ve got countless numbers of books. | 
| 昨日はビールを何杯も飲みました。 | 
| Yesterday, I drank so many beers. | 
| お店のケーキが大人気です。何個も売ります。 | 
| That shops cakes are very popular—they sell untold numbers. | 
何【counter】か〜ある
With the question particle, the meaning becomes “several”. The use of か makes it an embedded question, as if the speaker is asking themselves what the quantity is.
| テーブルの上には本が何冊かあります。 | 
| There are several books on top of the table. | 
| いくつかの提案を説明します。 | 
| I will explain several proposals. |