最初の部分、"I can understand, but" は「聞き取りはできますが」という意味です。「理解のことが出来る」を表します。
そして、"I'm not good at speaking" は「喋るのが苦手です」という意味です。「上手に話せない」を指します。「～苦手です」は英語で、"I'm not good at ○○ "と言います。
したがって、"I can understand, but I'm not good at speaking" は「聞き取りはでいますが喋るのが苦手です。」と翻訳できます。
聞き取りは聞くって意味で listen とも言えると思います。
喋るはスピーキングのことに関してであれば speaking でも
良いのですが会話をするに近い意味でしたら talking の方が
良いかもしれません。
会話を作ると言いたい場合は make a conversation の表現を
使うのも可。
「会話を作るのが苦手です」
"I'm not good at making conversations" など
I have good listening and understanding skills but not my speaking!
Some of my English skills are better than my speaking skills!
When learning a new language, everything is called skill, like, listening skills, speaking skills, and understanding skills.
"I can hear and understand what you are saying but I don't have the vocabulary to express myself."
"I understand what you are saying but my I am still building my vocabulary."
"I have good listening and understanding skills but my speaking skill is not that good!"
"Some of my English skills are better than my speaking skills!"
新しい言語を学ぶときは、あらゆることが "skill" という言葉で表されます。
例えば：
"listening skills"（リスニング力）
"speaking skills"（スピーキング力）
"understanding skills"（理解力）
"I can hear and understand what you are saying but I don't have the vocabulary to express myself."（あなたの言っていることは分かりますが、自分の気持ちを伝えるボキャブラリーがありません）
"I understand what you are saying but my I am still building my vocabulary."（あなたの言っていることは分かりますが、まだボキャブラリーがありません）
"I have good listening and understanding skills but my speaking skill is not that good!"（聞き取って理解することはできますが、話すのが苦手です）
"Some of my English skills are better than my speaking skills!"（英語を話すのが苦手です）
If you have a high listening ability but a low fluency ability and want to tell the person you are talking to this, you can say "I can't articulate my thoughts" while also telling them "I understand what you're saying". Articulate means you can't form the words necessary to say what you want to say.
リスニングが得意だけれど、流暢でないことを相手に伝えたいなら、"I understand what you're saying".（あなたが何と言ったのかわかります）と言って、"I can't articulate my thoughts"（自分の考えを伝えることができません）と言うといいでしょう。Articulate とは、自分の言いたいことをはっきりと言葉で表すことができないということです。
Listening comes easy for me, but speaking is my downfall.
Listening is no problem, but talking gives me trouble.
In American English these are both common ways to express this idea. 'Comes easy for me' is a phrase to describe something we are good at or skilled in. We often use the word 'downfall' to refer to something that is not only difficult but also causes us to give in to the temptation of something that ends up causing us harm, e.g.: 'I can't resist drinking Vodka; it's my downfall.' So in this case -- 'speaking is my downfall' --perhaps the person doesn't think before speaking, and says things to offend those around them.
上記どちらも、アメリカ英語でこれについて表す一般的な言い方です。
'comes easy for me' は、得意とすることを表すフレーズです。
'downfall' は、単に難しいだけでなくその人に害を与えるものをいいます。
例えば：
'I can't resist drinking Vodka; it's my downfall.'（ウオツカの誘惑に勝てません。私の破滅の原因です）
ですから、この場合の
'speaking is my downfall'（スピーキングが私の破滅の原因です）
もしかしたら、あまり考えずに話して周りを不快にさせることがあるのかもしれません。
My listening skills are better than my speaking skills.
It's hard for me to speak, but I can understand what I hear.
"My listening skills are better than my speaking skills."
Skill - This is talking about your ability to do something. In this sentence, we read that your listening skills are better or higher than your speaking skills.
"It's hard for me to speak, but I can understand what I hear."
Hard - difficult, something you struggle at.
Understand - Hear and know what was said.
"My listening skills are better than my speaking skills."（スピーキングよりもリスニングの方が得意です）
Skill - これは何かをする能力をいいます。この文では「スピーキングよりもリスニングの方が得意」と伝えています。
"It's hard for me to speak, but I can understand what I hear."（話すのは苦手ですが、聞いたことは分かります）
Hard - 難しい。苦手なこと。
Understand - 聞いて理解すること。
I struggle to speak but I am able to understand just fine
I have no problem listening and understanding but I find it difficult to speak English
"I struggle to speak but I am able to understand just fine"
To "Struggle" is often used to describe difficulty in something ex. "I struggle to get up in the morning".
"I have no problem listening and understanding but I find it difficult to speak English"
Is a causal expression, To have 'no problem' in something often refers that you find something relatively easy.
"I struggle to speak but I am able to understand just fine"（話すのは苦手ですか、聞き取ることはできます）
= "Struggle" は苦手なことを表すときによく使われます。
例：
"I struggle to get up in the morning"（朝起きるのが苦手です）
"I have no problem listening and understanding but I find it difficult to speak English"（聞き取ることはできますが、話すのが苦手です）
= カジュアルな言い方です。'To have no problem in something' は、あることが比較的簡単にできることを表します。
アメリカ合衆国 
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